# Simple mods worth it ???



## Ursus (Sep 23, 2004)

Hi all, 
New to the forum and a new GTO owner (I've had it just under a week).
I'm wondering if anyone has any experience with some of the simpler mods, like the K & N filtercharger air cleaner conversion, or adding a Granatelli MAF 
sensor. I realize both will give slight bumps in preformance, but are they worth the time/trouble???
Any thoughts ?


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## TORRIDONE (Sep 14, 2004)

No expert here but in IMO less restrictive induction or more air is a plus but it depends how good or bad the stock intake is ! Maf replacement I don't think this does much unless you have a seriously modified motor! You can do a search on the corvette forum for maf replacement posts good or bad? same motor as 97 to 04 C-5 in your GTO  

Robert


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## powder (Sep 29, 2004)

yes an aftermarket intake will help... not much but it will make it sound a little meaner. and it will give you a couple hp gain. larger MAF is for forced induction or N2O applications. if you want decent gains for an easy mod, go for aftermarket MANDREL bent exhaust and headers. another thing w/ the MAF is most of the time you need to have flow matched injectors that are calibrated for that particular sized MAF. something to think about. 

and does anyone know if they are making a s/c for the GTO anytime soon?


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## BRIAN P. EWING (Aug 7, 2004)

If S/c Means Supercharger Then Magnuson Has 1 Available.


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## tbush (Sep 14, 2004)

*Breath in, breath out mods for 2004 GTO*

I am having a baseline dyno tomorrow. We are then installing the predator program in the PCM. Then another dyno. On Monday, the dealer is installling JBA headers, Granitelli MAF, 80mm throttle body, and cold air induction. The following Monday, back to the dyno. I will post the results.


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## GlennH (Sep 22, 2004)

Got my Predator today and played with it this evening. This car is so fast anyway I'm not sure if I can say it's any faster, but, I sure like the shifts. I now get third gear scratch without being at full throttle. I installed the pre-programmed 'performance' tune and then did a little modifying on the shift time, shift pressure, and upshift MPH & RPM. I'm a little disappointed that, even after modifying the shift times to not shift until I reach 41 MPH or 6,300 RPM, it still shifts to second quickly when I'm not putting much of a load on the engine. They should have put a manual shift on the GTO where you slide the shifter over to manual and hit it up or down to shift the gears yourself. The Predator comes with a 30 day money back guarantee but I can't imagine taking it back...I think it was worth the money.


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## George8211 (Sep 21, 2004)

Nice to see these performance threads  


The small bolts will do small things in the hp world. IMHO it's best to save up for a real mod, like a head cam kit... Then you bolt on 100 hp in one wack, instead of 4 hp at a time.

Start talking to turner and pick their brain for ideas... then share.


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## powder (Sep 29, 2004)

GlennH said:


> Got my Predator today and played with it this evening. This car is so fast anyway I'm not sure if I can say it's any faster, but, I sure like the shifts. I now get third gear scratch without being at full throttle. I installed the pre-programmed 'performance' tune and then did a little modifying on the shift time, shift pressure, and upshift MPH & RPM. I'm a little disappointed that, even after modifying the shift times to not shift until I reach 41 MPH or 6,300 RPM, it still shifts to second quickly when I'm not putting much of a load on the engine. They should have put a manual shift on the GTO where you slide the shifter over to manual and hit it up or down to shift the gears yourself. The Predator comes with a 30 day money back guarantee but I can't imagine taking it back...I think it was worth the money.


from what i understand the '05 or maybe later will have that tiptronic shift option w/ the ATX.


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## powder (Sep 29, 2004)

tbush said:


> I am having a baseline dyno tomorrow. We are then installing the predator program in the PCM. Then another dyno. On Monday, the dealer is installling JBA headers, Granitelli MAF, 80mm throttle body, and cold air induction. The following Monday, back to the dyno. I will post the results.


what, no injectors? i can forsee problems w/ that. my friend put a larger MAF on his car and it would stall after a few seconds of running cuz his injectors weren't calibrated for that particular sized MAF. i could be wrong but i think its the same w/ all cars... i would like to know if im wrong though so any input would be cool.


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## tbush (Sep 14, 2004)

*Predator results 2004 GTO*

Ran the baseline dyno today. Results were 283hp/315tq. After five tuning runs,
we achieved 296hp/324tq. We noticed the factory timing was very conservative at 12 degrees. We change to a higher setting of 23 degrees. Air fuel ratio(AFR) was very rich, especially in the higher band (4000 and up). We leaned the mixture but left headroom for the Granatelli MAF, as it leans the high end also. Next week we are having the headers, throttle body, MAF, and cold air induction installed. WE will try another dyno after(Oct. 12 or later)

Terry


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## tbush (Sep 14, 2004)

*Performance results 2004 GTO*

Forgot the most important part. A test drive after exhibited very nice shift characteristics. During the dyno, we noticed a horsepower roll-off at 5500, so we moved the shift points back a little. I believe this roll-off will be fixed with the headers and other breathing mods. Although not a great hp jump, the feel is great! Can't wait to finish the mods!

Terry


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## powder (Sep 29, 2004)

tbush said:


> Ran the baseline dyno today. Results were 283hp/315tq. After five tuning runs,
> we achieved 296hp/324tq. We noticed the factory timing was very conservative at 12 degrees. We change to a higher setting of 23 degrees. Air fuel ratio(AFR) was very rich, especially in the higher band (4000 and up). We leaned the mixture but left headroom for the Granatelli MAF, as it leans the high end also. Next week we are having the headers, throttle body, MAF, and cold air induction installed. WE will try another dyno after(Oct. 12 or later)
> 
> Terry


 it dyno'd 65+ hp less than at the flywheel and 50 less tq? um... that sounds pretty rediculous to me... im mean, call me a dumbass but aren't whp #'s usually only about 10-20 less than flywheel hp #'s? or is that just w/ front wheel drive?


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## tbush (Sep 14, 2004)

*350hp*

The 350HP is crankshaft HP. In general, Manuals loss 15% and auto's loss 20% to the rear wheels. 296/.8= 370 crank hp. 

Terry


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## 61 Bel Air (Aug 6, 2004)

powder said:


> it dyno'd 65+ hp less than at the flywheel and 50 less tq? um... that sounds pretty rediculous to me... im mean, call me a dumbass but aren't whp #'s usually only about 10-20 less than flywheel hp #'s? or is that just w/ front wheel drive?


Not all Dynos will give the same result. A "Dynojet" dyno will give you higher HP numbers than a "Mustang" dyno. I think the "Mustang" has a load on the rollers which would give you lower RWHP.


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## Ursus (Sep 23, 2004)

Well, added the K & N aircharger.
Don't know, but "feels" faster and more responsive throttle.
And it just looks good underhood !!! :cool


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## GlennH (Sep 22, 2004)

I have that air charger ordered and should get it tomorrow. Did you install it yourself? I was going to try to do it but wondered how hard it was to do. Anyone ever tried it themselves?


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## powder (Sep 29, 2004)

its pretty easy on any car... just a few hand tools and 30-60 minutes of your time. bolts right in...


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## PJC_GTO (Sep 23, 2004)

Here is a link to the K&N filter installation instructions. Looks straight forward and includes pictures.
http://www.kandn.com/instructions/63-1099.pdf


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## chagloch (Sep 24, 2004)

I put one in my GTO this past weekend. I know absolutely nothing about cars, but my GTO has inspired my to start learning. I got the K&N kit and was supposed to get help from a friend, but couldn't wait for him to get there. So I read the instructions, they didn't look to tough, so I dug in and got to work. I had it installed in 2 hours, and I would have to say that it is pretty easy if you can follow instructions.

Chuck


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## PJC_GTO (Sep 23, 2004)

What did you have to pay for that unit?


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## GlennH (Sep 22, 2004)

I looked all over online and called everyone I could find and none of them had it in stock. They all said it would be 10 days to 2 weeks before I got it. Being the impatient type, I found it here in town for $275 plus tax...about $20 or so more than online. I haven't picked it up yet but was promised it would be at O'Reilly by 4:00 this afternoon. I bought my Predator Programmer at O'Reilly and paid the same $420 I found it for online. I also got the front seat smokers package (ashtray and lighter) from my dealer and ended up having that installed...$165 to have a place to doose my nasty cigarettes :shutme . Now I need 18" wheels and tires, a cat-back system and a ram air hood and I'll be in heaven.


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## powder (Sep 29, 2004)

im putting 20's on mine when i get it...


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## chagloch (Sep 24, 2004)

PJC_GTO said:


> What did you have to pay for that unit?


I paid 259.35 w/free shipping from ajusa.com

They had the part on my doorstep in less than a week.

Chuck


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## Ursus (Sep 23, 2004)

PJC_GTO said:


> What did you have to pay for that unit?


After checking online and finding it anywhere from 259.99-399.99(K&N direct)
I saw one offered on Ebay for $229.00 + $12.00 S/H = $241.00 to my door.
I'm not a real "shade tree" mechanic and it took me about 25 min. taking my time to insure I didn't break anything. Had all the tools handy except a T-30 Torex socket, which added $2.99 to my total cost...I can live with that. 
Now I need a granetelli MAF (set up for cold air induction) and a Diablo tuner.
THEN I'll get the ram air hood and 19"s, by then I'll probably need the tires anyway !!!


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## Ursus (Sep 23, 2004)

Ursus said:


> After checking online and finding it anywhere from 259.99-399.99(K&N direct)
> I saw one offered on Ebay for $229.00 + $12.00 S/H = $241.00 to my door.


The guy I got mine from offers one a week on Ebay, no bid just click the buy it now button. Search for 2004 GTO, or his seller name "Gforceautosports"
I am in not connected to this guy in any way, just info for those that want it.


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## Whiteshadow (Sep 28, 2004)

Too bad I didn't chime in earlier, but Lingenfelter had an AWESOME special last week (I believe it was a three day deal) but they were selling their new intake for $289.00+shipping as an introductory price. It's now listed as $399+shipping. Pretty neat looking setup though. 

Here's a link: http://www.lingenfelter.com/lingenfelter/product.asp?dept_id=16&pf_id=596


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## leaftye (Oct 11, 2004)

I can't emphasize strongly enough to stay away from aftermarket MAFs. If it's the only mod, it may provide a couple extra horsepower since it lies to the PCM and leans out the air/fuel mixture to provide the extra power. All to often aftermarket and modded MAFs cause tip-in KR and other tuning problems. I modded my MAF and had a hell of a time trying to tune out tip-in KR, and other problems that didn't seem to make any sense. I learned that my ram air intake was forcing the bulk of the air to flow thru the top of my descreened MAF and missing the wires so the MAF wouldn't meter the air flow correctly. I started looking at aftermarket MAFs, but after tons of reading on ls1.com and ls1tech.com, I found that most guys with aftermarket or modded MAFs were having the same problems, and were going back to stock MAFs. I bought a stock unmodified MAF from a guy on the forum, went back to tuning, and easily got rid of the tip-in KR. Now I'm tuning the spark advance across the board to optimize power at all throttle positions and rpm's. As far as getting Predator, I think it's a waste of money. Spend the money on HPTuners and tune your car properly. FWIW, I'll be glad to help with tuning where I can.


Eugene


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## Guest (Oct 12, 2004)

I am a dentist without much knowledge on the subject. As soon as I got my GTO my neighbors told me to get a Borla exhaust and a KN CAI for starters. They told me I would get improved hp and torque. I almost did it, taking their word for granted since they all do these simple mods on their Mustangs religiously. Yes, I live in a neighborhood where Mustangs and Cobras are weekend toys. Still, I am the kind of guy that looks deeper into things. I said to myself: "Antonio, before you change a single bolt on that car first find out why the Pontiac engineer put it there for in the first place." I read a little here, came to thse forums, and talked to some people here and there. One of my dental assistants wanted me to put in a supercharger!

Question is why would I need a KN CAI system. Answer is: to make more air available for intake into the combustion chamber. Is that so? I am not too sure it really works for the GTO. It may very well work for other cars; but that does not necessarily holds true for the GTO. My best impression so far is that this is a fallacy and I will tell you why.

First, the GTO has a fine design that "ducts cool air into the intake manifold from a road-level inlet tucked away out of sight behind the front air dam." That is why the GTO does not have an unsightly ram air scoop on top of the hood. The faster the car goes the more air is inducted into the air dam and into the manifold. It is like having a real aircharger. Therefore, I undestand that air flows thru the wide mouth front air dam and is forced through a duct into the airbox, thru the filter and into the manifold. As the car goes faster it will certainly gulp more air. A basic principle to observe is that the cooler the air, the denser it is and having more air mass in a smaller volume means that ther will be more oxygen available for a more powerful combustion, thus " a bigger bang". Once the air gets to where it is supposed to go The GTO has an ultrafast 24 MHz P59 Powertrain Control Module (PCM) that controls 17 engine related functions that includes manifold air pressure, incoming air density and its temperature to feed Sequential Port Fuel Injection system that provides you with "precise amounts of air/fuel mixture to each cylinder", critical for optimum performance. I already paid for all of that. That's in your car, a well made car.

Putting a KN or similar CAI thing in your car will ruin all of this beautiful engineering. reason is simple. First, you practically bypass the duct system because the seal is broken as you remove the airbox, which is airtight from stock. Air will still flow thru the air dam but as you remove the airbox the air will escape and mix with under the hood hot air creating a turbulence. The engine will suck hotter less dense and actually unpressurized air from beneath the hood and you would have ruined all that Pontiac engineers have made for you and you paid for.

Ohh, but someone put a dyno and it read some hp increase. BS, the car is sitting there with the hood up and all you have done is to open a larger hole for the LS1 to breath passive air. The car is not running with the hood down. If you want to race paper races go ahead and take the whole filter system off and leave the air port wide open. As the GTO accelerates it gulps forced air into the dam, the duct and the manifold. With the KN thing you loose all of that and risk putting oil into your fuel injection system. Them KN filters use oil to filter.

The Pontiac enginners did a lot of research on the exhaust system. They designed a Low Restriction Dual Exhaust System. They say that their LS1 engine uses "8 cubic feet of air per second" requiring "an exceptionally high- flow, low restriction intake and exhaut system. That is why they made a dual exhaust totally independent designed to maximize flow. They researched on computer models more than 50 potential systems and actually built and tested more than half a dozen systems to come up with a great sound and performance. The Borla dealer told me right out that his system would add at least 10 hp to the tire increase. I say it is BS. I cannot believe that Borla consistenly comes up with an exhaust system for every car on the market outperforming every engineer in the world.

If you need a faster more powerful car get an 05' or do serious modifications to your car like a supercharger or a turbocharger, take the engine apart and add new cams and converters and manifolds and stick in a coulple mules and several horses if you wish, like they do for NASCAR, and ruin your GTO for the weekend.

Save your money and just put some nice Mobil 1 in it and change the oil regularily and use premium gasoline from EXXON.

I had my say. I would like to see some coments.

Ohh, I ALMOST FORGOT! I looked into the functional ram air hoods. I tell you about that too. Best I ahve seen is the Scorpion for it has a funtional ram air and an air tight airbos with a KN cone filter. Then I took a hard look into it. It is a piece of crap. Tell you why. As air come in from the air dam and into the airbox it goes out the ram air scoops defeating the GTO cold air induction intake. I don't think it works. If you want some air scoops have them for looks and spoil your air resistance and to slow your car up. By any means don't mess up the GTO Cold Air induction System that comes with your car.


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## BRIAN P. EWING (Aug 7, 2004)

I'm Far From An Expert But I Believe A Cat-back Exhast From Borla,corsa,or Slp Will Add Some Extra Ponies To The Gto Due To Them Being A Better Breathing And Less Restrictive System's Than The Factory One. There's A Post Where Someone Took Off Their Stock Exhaust And You'll Be Able To Tell With All Of The Evident Crimping In The Stock System That There Is Horsepower To Be Gained By Replacing It. I'm Interested To Know If Anyone Has Added One Of The Above Sytems?


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## kevracer (Sep 27, 2004)

*K & N cold air intake*

I read with interest adearmas' post. I too come from the school that thinks that the GM designers designed the intake as they did for good reasons. I am also concerned about how the dealer would react as far as warranty? Any comments?


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## kevracer (Sep 27, 2004)

*K & N cold air intake and emissions*

I read on the K & N website that (quoting here) "AirCharger Kits are NOT legal for sale or use on pollution controlled vehicles in some states. These kits replace the original air filter box and may eliminate or defeat some emission controls." I noticed also that this item is not CARB exempt. Besides the possible warranty problems, it seems that use of the AirCharger could lead to emission testing problems down the road?


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## GTO TOO (Sep 10, 2004)

I promised to stay out of these threads. BUT !! Here goes. 
Simple mods are NOT worth it. To make real HP improvements you need to increase airflow as all the threads have said. The cork in most engines is the airflow in the heads ( and cam design ). A stock Mass airflow meter will flow more air than the ports. As long as I'm on Mass airflow meters, here's another fact from fiction:

MAF's measure airflow, but they are not ALL the same. The way a MAF reads airflow ( and converts it to a true MASS airflow reading ) is a science. The airflow through a sensor is NOT homogeneous with regards to density ( MASS ) As airflow rates change and RPM's vary the actual "velocity profile" through the MAF also changes. Velocity profile means the air in the meter that flows past the measurement unit, in the meter, is not a constant density. Where the most dense air mass resides as it passes through the meter changes with airflow and RPM. ( you can have the same velocity at many different RPM's, and both influence the velocity profile of the mass of air going past the meter )Therefore all MAF's used in production applications are calibrated specificly for that application. The induction system and aircleaner assembly have a larger influence on the output of the meter in it's ability to output true "Mass of air" reading. Aftermarket MAF's cannot be properly calibrated for an given application because the conversion of the meter output to MASS air is done the ECM software. ( AFTER market guys can put ONE MAF on one car and try to make the output of their meter match, but all they have done is make it match THAT CAR. And the calibration they have come up with cannot be "KNOWN" to function on another car of even the same components. ) They may appear to "work" as the fuel system can learn a fairly large errors. However, that learning only applies to "closed-loop" control, and not all fueling is closed loop. Manufacturers use the known MAF output of a population of sensors to match the "norm" of the production cars, with a calibration that best matches the "known" induction system design the car was built with. 
The same holds true for the guys that remove the "screens" in production MAF. That screens area is well accounted for in sizing the MAF to the engine. And the "screen" is actually a flow straightener that allows the MAF to output a true Mass of Air reading. Just because there is an output from a genric MAF does not mean that reading is actual Mass of Air. ( that is dependant on the calibration of the meter to the application. ) And without true mass the fueling system uses it's "learning range" to correct the closed loop fuleing. But that does not mean all the fueling over the entire operating range of the engine is correct.

Point two sorry technical answers are rarely short if you wish to truely understand the issue ) Forced air induction is only good to ensure cold fresh air. That is great for power, but not normally good for best driving on the street. Before the engine warms fully, some warm induction helps combustion and makes your car drive good as it warms up. For the minor benifit of a small ( very small increase in output ) you suffer poor engine preformance in cold weather. Secondly, induction systems are designed to do more than just flow max. air rate. Just a few of the things they are designed to do; they must keep water out of the engine in the rain, keep snow and sleet from freezing on the throttle blade, and supply sufficient air to the engine. Do you think the striaght CAI pipes folks put on their engines are designed to protect the durablity of the engine over time?? If you maximize any ONE aspect of a systems performance ( MOST AIR POSSIBLE ) it is usually at the cost of another important design aspect. System design is a balance of many different desired functions. If you don't know all the consequences of a change, those unintented consequences can be costly over the life of the engine.

And Lastly,you cannot drive FAST enough to effectively force air into an engine at high RPM's.
The velocity of the airflow entering through the ports is dependant on a delta pressure between the piston "drawing air in" and the pressure in the manifold.
The difference in maniflod pressure going even 100 MPH ( not to mention the restrictive nature of an airclearner of "any kind" ) through the normal size port opening of even after market CAI tubes, is exponetially small compared to the piston velocity, and is of a negligable effect. If you could make the forced air induction duct large enough to gain a mechanical advantage and pressurize the manifold it would work. Do you know how large the intake port opening would need to be vs. the duct cross sectional area to gain any pressure? HUGE. The actual airflow velocity at the port during intake valve opening is exponetially larger than the difference in zero MPH vs. 100 MPH.It takes a turbo or supercharger to actually gain mechanical pressurization in the manifold. Sticking a duct into the wind at speed does not effectively increase pressure on the manifold side of the valve.

Bottom line to gain real horsepower you must change engine parts. Small modifications will result in very small improvements in performance. The downside of "messing" with a production engine with "little" tweaks", is the unintended consequences of durablity and asking more questions like" why is my XXXX CEL light on?" Modern engines are very complicated SYSTEMS. Using trial and error to find "work around " solutions to the "tweaks" can take a lot of time effort and money without a corrisponding increase in real performance gains. My random thoughts.


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## leaftye (Oct 11, 2004)

GTO TOO, great points, and AFAIK, correct on all counts. In a big MAF thread on another forum, the conclusion for the MAF problems people were having is that although aftermarket and ported MAFs were bigger, the sensor element was exactly the same as the stock unit. It could flow more air, but the problem is that if the same amount of air was moved thru the stock and aftermarket MAFs, the air would flow slower thru aftermarket MAF, so that MAF would think there was less air. That would cause a lean situation. This is also partly the reason we believed we were getting tip-in KR. Basically the air would quickly demand more air, but the modded MAF wouldn't pick up the increased airflow as quickly as the smaller stock MAF, so there would be KR for a short time.

My intake also forces air to flow thru the top of the MAF, which is cool when there's a screen installed, but without the screen, most of the airflow could skip the sensors wires entirely.

MAFs also are calibrated along about ten points in the PCM. Aftermarket MAFs are recalibrated with a single resister. Hmm...ten calibration points recalibrated with a 10 cent resister?? Recipe for problems? I think so, and so do many others on the LS1 and Corvette boards.

I'm with you on the heads. The heads are where power is made. It's the heart of the engine. Only problem is that it's not fun to swap. An easier swap is headers, specifically long tube headers. Any shortie header isn't worth it in my opinion. Long tube headers almost always improved low end torque, high end horsepower, drop weight, and makes nice sounds. 

When looking for parts, we all need to recognize that these engines have been around since '97. It doesn't matter if the engine is in a Trans Am, Corvette, SSR, or GTO, there's many parts that can be used on all platforms, and someone has probably already tried whatever part we're looking at.

Eugene


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## Guest (Oct 13, 2004)

Congratulations. Nicely put and evidently knowlegeable. 

My sister 's in law husband bought a Mitsubisi Eclipse some years ago. Young guy there, truly believes he was born to be a NASCAR driver. A decal on his rear windshield says "Will race for food". Long story short he replaced the exhaust system, the air intake, hijacked the computer system with one of them Predator type of electronic things that he can actually program the various parameters of functionality, he changed the wheels and tire size, he did this and did that. He ruined the car, period and lost his warranty. Ended up discarding the Eclipse and his dad had to buy him anew car. Now he's got a Mitsubishi Evolution. With what he paid for both cars he could be driving a Corvette with some spare change for the tolls.

So far I have not seen any simple modification that can be safely done to our GTO's. I'll keep my original filter on. I want my LS1 to breath clean air. I was reading on another forum that when you change the air intake system the temperature sensor is not designed for the altered airflow stream due to the size of the tube and actually cannot read the temperature nor the amount of air coming in can be properly estimated electronically thus the computer works with false parameters and you actually loose hp. Something to that effect.

Point is, let's face it, most of us really do not know enough to go around modifying our cars and truly understand the full scope of what we are doing. I don't think it is as easy as going to the shelves in the auto parts store and buying some magic trick that makes our cars gain hp. My neighbors, the Mustang gang there, told me about the KN airfilters and how it increases the hp in their cars. I asked how do you know it actually does; and, they answered because you can hear the difference. "Now my car sort of gives a big gulp when I start it and then it has this throaty noise like it is going to turn off and that let's me know I got the power." I answered that from a medical point of view it sounds like his car is sick.

What kind of science is that? Everyday as I listen to the news on CNN or Fox I see this add about the loosing weight magic pills that cost $150.00 a bottle claiming it controls the hormones that make you gain weight. Everyday I see that add in all channels simultaneously. It costs a fortune to advertise that much in prime time; yet, they keep on advertising. They do it because if you repeat somthing, no matter how stupid it is, enough times people will start believing it is true. Same story with all these so called simple modifications as far as I can see.

One must conced that there's some guys around, maybe here too, that have the knowledge and resources to play around with their cars and probably actually increase the hp. Some guys even use Nitro to win races. Now, if you want to burn gas in the presence of Nitro that's all fine with me as long as you know you are ruining your engine, especially these aluminum engines. These LS1 engines are good engines but the design has its indications. Exploding dynamite sticks inside the combustion chamgers is not one of them.


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## MaxHax (Oct 16, 2004)

I have never seen a forum so anti mod hehe.

Looking at the exhaust from the exhaust manifold all the way to the tips I would have to say there is lots of gains to be found there. If you don't want to MOD then buy a Z06 

I agree about the MAF and tuning but exaust and intake mods are always good for power and a better sounding muscle car on pretty much any LS1 and this is my 3rd one.

Having said all that the MAF and TB is a waste of dough as is the Diablo but I DID just order a catback today with a CAI and I expect some RWHP, TQ and a meaner sounding ride. I will post my results. I also ordered a BMR STB so it will look cool if anything 

Nice to see the technical posts though instead of a bunch od vendors trying to sell you stuff it's aprecited because I have been on LS1.com since 1999 and I know all too well that some Vendors will tell you anything to make a buck! Keep it simple and plan your mod path. If you want to go FI or N20 expect lots of tuning and lots up maitenance and upkeep and if you don't want constant user maintenace don't go FI. If you do plan on going FI don't waste 500 toying with CAI's and MAF's etc because most kits come with their own CAI etc. So I guess my 2 cents is plan your goal first then mod from there. I am staying FI and will probably do internal engine work with that hand polished LS1 Intake because in my book looks count too!


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## GTO TOO (Sep 10, 2004)

MAXHAX, 
You misunderstood what I was trying to say. If not anti-mod. The question was are simple mods worth it. You too seem to agree for all the greif and unintended consequences they WILL cause, simple mods are not worth the hassles they will present. Power increase vs. cost in time and effort are not worth IT. The cork in the LS1 for increased airflow ( that's what makes power ) is in the heads and camshaft. If you want to "mod" that would be worth the effort. You may see a small gian with the catback system, but once again, do you know the consquences. Just because you make a change after the convertor does not mean you are not effecting other operating conditions. The flow through the exhaust system can have issues with CEL lights. I've read the other forums were guys talk about warranty issues and how one change can not possibly casue what ever problem they have wrought unto themselves. The truth is any increase in flow either upstream or downstream of the engine can and does effect both engine fueling ( all fueling is not closed-loop ) and diagnostic feedback issues. There is risk of turning on CEL's that will not go away. You can turn off a CEL but if you do not change the reason it came on, you have fixed nothing by turning it OFF. Again I'm not preaching no mods, I'm merely questioning, does the person making a mod know the other things that can be changed. ( I doubt it, with out testing ) Also, CEL (diagnostic lights ) do not just light up. A code can and will set in the ECM before the light is on. Different codes have varing failure rates before setting the light. However, when some codes are set, some engine functions are disabled and some functions change to prevent more damage when a "CEL" condition exsists. ( whether a light is on or not !!)How the engine functions with a fault detected ( not just a light on ) can negate any positive benefit of the change. Making MODs without full knowledge of the system is like kissing in the dark, It might be great or you might be in for a big suprise when the lights come on !!! GOOD LUCK !

P.S. 
I've rarely read a post that states I change the XXX valve and saw no improvement in power. Nope most that make a change can imediately tell they have made a huge gain in power. That's the way the mind works, that's why we use dyno's.


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## MaxHax (Oct 16, 2004)

Hi,

I think we are on the same page and apreciate the good advice here. I wouldn't be opening up my exhaust if I didn't plan on increasing the HP and torque so it's where I am starting and an easy mod. This is what I mean by having a modification path/goal.

I made a typo above I do not plan on going FI, but N/A sorry. I am burned out on the constant maintenance of FI.

As for CEL's I have never recieved one from a catback EVER. I have only recieved CEL's or SES's when I mess with the cats and 02 simms.

I may be wrong but a catback doesn't change the 02 simm's and cats does it? It didn't on my other cars. Is there a link I can read on this I admit I am knew to the GTO. Even with headers as long as you kept the cats and 02 simm's I wouldn't expect a CEL but if I did I would not rest until it was diagnosed and fixed and if this "catback" is known to cause CEL's I sure would like to know about it before I install it! I do plan on getting headers and adding a 3200 stall TC soon to increase the low end.

Because if that is the case (CEL's from catbacks) I will find out why and/or send it back. I learned a whole bunch in 2000 from ls1tech.com from people like you and adearmas who tell it like it is. I want to increase the amount of air in and increase the amount of exhaust out and it has already been shipped. To me it's hot rod 101 up to this point then comes the tuning, which I usually do last after all is done that I want done as far as A/F and timing.

It is an SLP catback and an SLP CAI W/ 4 inch tube. I also got a BMR STB and SFC and they are tried and true for handling on my other F-Bods. I plan on the new heads and cams in the future and a larger polished intake to sit on top of it all. If you see something wrong I am always open to learn on this car. I know CAI's will always be a great debate over stock air boxes but this new info about CEL's from a catback admittely has me concerned so I will be hoping for a link or feedback from others who have done a catback (kept the cats stock) and whether they got a CEL or not. Thanks!


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## NEW2GTO (Nov 3, 2004)

I am wanting to order an 05 GTO as my graduation from college present in a few months. I really want to have a great sound screaming out the rear end of an already impressive 400 HP 6.0. Can a cat-back system really be that bad for the car. Corsa is a liscensed GM parts dealer for goodness sake. If all else fails shouldn't they know how to fix any of the computer problems? I mean they actually help do the testing so they know whats going on with all the internal workings correct? SLP should be the same being that they had packages that GM offered.

I am not looking to turn mine into a racecar or dragstrip, I just want it to sound as mean as it truely is. I want fast, fun and reliable car that sounds great. If I am making a racecar I'll start with a Vette.

What are your recommendations? I also want some meaner looking wheels and tires. 19-20 inchers with 265-275 tires in the rear. I have heard of some spacing problems. What are some feasible non $2000 options for fixing that?


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## GTO-TO-GO (Oct 15, 2004)

If you have the tools and the time a GM high performance LS-6 cam from ther parts catalog and some LS-6 heads could give you the HP you desire.
Cam part # is 12565308 and will change the duration and lift to send more air thru the heads. LS-6 head part # is 12564824 and the have a 3cc smaller combustion chamber to increase compression.
The cam however will give you the bigest HP boost and changing the stock mufflers to some good Flo-masters will give you the sound thats cool.
You will need to change the timing to match the nae cam but having done this to several cars, you will loose some low end but will gain HP in the mid range and the top end. Some fine tuning will be needed with any engine mods.

I haven't called my local dealer to see if this swap is carb legal here in Calif.
Call you dealer to see.

GTO-TO-GO


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## yesbill (Sep 23, 2004)

I could not of said it better. Little mods are almost always pschological not physical. We all want a bigger kick in the pants but we seldom get what we want by drinking mouse milk. Thanks.


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## LarryM (Aug 17, 2004)

yesbill said:


> I could not of said it better. Little mods are almost always pschological not physical. We all want a bigger kick in the pants but we seldom get what we want by drinking mouse milk. Thanks.


??? Mouse milk???? You must have a realllly tiny stool and bucket man! LOL!!!


---Larry


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## lambertgoat (Oct 24, 2004)

TORRIDONE said:


> No expert here but in IMO less restrictive induction or more air is a plus but it depends how good or bad the stock intake is ! Maf replacement I don't think this does much unless you have a seriously modified motor! You can do a search on the corvette forum for maf replacement posts good or bad? same motor as 97 to 04 C-5 in your GTO
> 
> Robert


stock intake is off the ls-6, one of the best out there, don't change it, uppers flow exellently(sp) simple cam change can offer 500 hp or better


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## GGTTOO (Oct 6, 2005)

Man what a depressing thread. Look I agree that the big gains will have to be done with engine modifications such as head work, larger injectors,cam etc., but if all you want is to mellow out or change the hp range slightly then some small mods work great. 

Most of us when we purchase the car do not have another 5 to 10 grand to get the proper engine work done and choose to selectively mod the car to make it our own. 

Let the mods flow, I say.
:willy:


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## smkdu (Sep 22, 2005)

I agree with the maf and exhaust setup but a lot of people like the split dual exhaust on the 05(me being one of them) and I really want a setup like that. So I planned on buying a manderel bent system and long tube headers b/c I plan on getting the 402 stroker kit. So if I'm gonna spend that much I really want the look and sound that a "Muscle Car" should have. :cheers


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## BOSSGTO (Oct 5, 2005)

After owning several GM and Ford factory hotrods, the last being a 01 C5 with a six speed; I'm convinced the manufacturers do not put their research in giving you the most for your $ but instead the least. 

Performance wise most everything needs to be upgraded unless you're buying an exotic "pure sports" vehicle.


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## ken (Jan 29, 2008)

new owner, just bought 2004 6sp about 1 mobth ago. Put k&n intake, its cool. want to get exhaust, but money is short. can you suggest a cheaper fix.


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## NJG8GT (Nov 14, 2007)

ken said:


> new owner, just bought 2004 6sp about 1 mobth ago. Put k&n intake, its cool. want to get exhaust, but money is short. can you suggest a cheaper fix.


delete resonator and throw on some Flowmaster super 44's!!!


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## ROBSGTO (Jul 6, 2008)

NJSierra said:


> delete resonator and throw on some Flowmaster super 44's!!!


I thought I saw somewhere that Flowmasters were more restrictive than others,is this true?


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## jradke123 (Apr 18, 2008)

i have flowmasters on mine and it was just fine and it sounded amazing when it was just that


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## Rukee (Feb 8, 2007)

ROBSGTO said:


> I thought I saw somewhere that Flowmasters were more restrictive than others,is this true?


I was always told a Flowmaster will flow more air then the same size straight pipe.


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## Chrisco (Mar 19, 2007)

ROBSGTO said:


> I thought I saw somewhere that Flowmasters were more restrictive than others,is this true?


I have heard this as well. That's why i went with spintech. I'm really happy I did that.


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## NJG8GT (Nov 14, 2007)

I believe anything other than a straight pipe your not going to get anything better flowing other than glass packs which will burn out and sound will change in time as the magnaflows will due to being packed with a sound deadening material...

Actuall the new Flowmaster Super 44 Series claim they have better flow than the Original 40 Series that is so ever popular... Any thing other than the above mentioned two like the 50 series, super 40 series, etc will give you some crazy annoying drone from what i am told by my local five star muffler man who has put on almost a dozen custom flowmaster exhaust systems int the past for me.... I have to tell you the ole sierra is sounding nasty with the original 40 series and split exhaust tips in rear..I'll have to post some clips when i get a chance like i did with the ole goat.... 

Aint no better sounding flow like flowmaster....That is why they call them the master..:lol::lol::lol:


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## greased (Jun 11, 2008)

powder said:


> what, no injectors? i can forsee problems w/ that. my friend put a larger MAF on his car and it would stall after a few seconds of running cuz his injectors weren't calibrated for that particular sized MAF. i could be wrong but i think its the same w/ all cars... i would like to know if im wrong though so any input would be cool.


DOH! as homer would say. 

there is no such thing as injectors "calibrated" for a certain MAF.
A MAF measures MASS AIR FLOW and aftermarket MAF is generally sized bigger to stop pegging which is caused by forced induction. The stock maf is only sized to handle a certain amount of air flow/ hour and an aftermarket maf fixes that. Since both the stock and aftermarket MAF must be able to send info to the stock computer they have to be on the same set of outputs (0-5v) (0-12000hz). since stock is limited at say 75 lbs/min of air flow it sends out a 5v signal at that flow. The aftermarket equivalent must be able to handle up to say 120 lbs/min of airflow. So the aftermarket equivalent might send out a signal of say 3.9v for the equivalent 75 lbs/min. Without recalibration of the stock Airflow tables, the computer will give enough gas for whatever 3.9v was with the stock maf. thats why your friends car was leaning out hardcore


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## NJG8GT (Nov 14, 2007)

On my 05 Silverado, I had the Jet programmer, TBS, K & N intake, Jet MAF, and hand no troubles what so ever...


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## Chrisco (Mar 19, 2007)

greased said:


> DOH! as homer would say.
> 
> there is no such thing as injectors "calibrated" for a certain MAF.
> A MAF measures MASS AIR FLOW and aftermarket MAF is generally sized bigger to stop pegging which is caused by forced induction. The stock maf is only sized to handle a certain amount of air flow/ hour and an aftermarket maf fixes that. Since both the stock and aftermarket MAF must be able to send info to the stock computer they have to be on the same set of outputs (0-5v) (0-12000hz). since stock is limited at say 75 lbs/min of air flow it sends out a 5v signal at that flow. The aftermarket equivalent must be able to handle up to say 120 lbs/min of airflow. So the aftermarket equivalent might send out a signal of say 3.9v for the equivalent 75 lbs/min. Without recalibration of the stock Airflow tables, the computer will give enough gas for whatever 3.9v was with the stock maf. thats why your friends car was leaning out hardcore



Perfectly said.


Oh and Spintech>Flowmaster any day of the week. :cool


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