# Best intake / Exhaust combo?



## asteng88 (Aug 26, 2004)

Hi all, just wanted to ask if anyone had modified their flow system and what is regarded as the best exhaust mfr in the US for performance exhausts.
I have used K&N air intakes in the UK and got impressive performance.

Thanks

Andrew


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## Guest (Oct 13, 2004)

*Don't throw away your money!*

04' GTO has all the factory installed, best and most efficient airintake/exhaust system, period. You go ahead and put some KN airintake and you will have your LS1 gulping hot less dense air. Your parameteters will go bezerk and probably end up contaminating your system with oil. Your LS1 pistons will take in air by negative pressure and, as it is, it has all the air availbale it can handle. You don't need anymore because the GTO takes air in through the air dam, plenty of cold , dense air and routs it through proper diameter ducting into the airbox with a nice filter and then into your manifold where intake diameter gets much smaller so it does not matter what else you do outside. All sensors and software is designed for specific dimmensions of your system. The GTo electronically adjusts itself for the proper fuel/air mixture (See your silver GTO catalog that explains all of that). The KN airintake system, as well as all others, what it does for you is to spoil the whole design to allow hot, under the hood, undesirable useless air into your car's engine probably shortening its life.

The GTO exhaust system has been carefully designed to maximaize air flow from your engine. GTO engineers went at great lenght to design this system. Please, don't spoil it with some off the shelf magic pill type of solution. Don't fall for these aftermarket useless ideas. 

Only way to actually increase significantly your vehicle's hp is to modify the engine which would take some finely tuned engineering to design, build and mantain. Unless your last name is Ford, Holden or GM don't get into it. Keep your GTO as it was designed for the job it was designed and take your money to enjoy a meal out with your gal. It is a powerhouse and a fantastic car as it is. It is a beautiful piece of engineering. If you still want more power get an 05' GTO.

Have fun driving it! I do.


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## TexasRealtor (Oct 4, 2004)

I'm not sure about CAI improvements, but here is a thread regarding the stock exhaust.

http://www.gtoforum.com/showthread.php?t=98


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## Tiger (Sep 26, 2004)

.......or........

Belive the dyno and install headers and a free-flow exhuast. There are only a few full systems out right now, but I haven't seen all the numbers, but any of them will be better then the stock system chock-full of flow robbing pinch points. I persoanlly like the looks of the side dump exhuast (and side skirts) offered through arrowheadperformance.com.

While adearmas is almost correct in saying that adding an entire intake system, with open element air filter, will suck in more hot air then the stock set-up, once moving, that effect is not nearly as pronounced. Add just a simple drop-in panel filter and you'll be doing yourself a favor.


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## GasTiresandOil (Aug 2, 2004)

I don't have the slightest idea about intakes because they are all sucking air from under the hood. Get one the sucks air from outside the engine bay and we'll talk.

As for exhaust, cut the stock exhaust off after the cats and add you own choice of exhaust. The stocker has a creese no more than a few inches from the exit of the cats. After the mufflers there is another creese in the exhaust and the two pipes cross over one another. I guess this is for equal length and sound. When my exhaust goes from 2 1/4 or 2 1/2, what ever is stock, down to a size no larger than a 1 1/2 creese you are creating significant back pressure and choking you engine.


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## Tiger (Sep 26, 2004)

I think I remember reading somewhere that the two pipes never actually 'cross-over', they are compeltly seperate from each other. The peice that looks like the x-over is actually welded shut....at least, thats what I read. Forget the reason stated as well, but it was a typical manufacturer's excuse.


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## TexasRealtor (Oct 4, 2004)

Tiger said:


> While adearmas is almost correct in saying that adding an entire intake system, with open element air filter, will suck in more hot air then the stock set-up, once moving, that effect is not nearly as pronouncedQUOTE]
> 
> Will the new hood with the scoops help bring cooler air into the engine compartment?


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## GasTiresandOil (Aug 2, 2004)

Tiger said:


> I think I remember reading somewhere that the two pipes never actually 'cross-over', they are compeltly seperate from each other. The peice that looks like the x-over is actually welded shut....at least, thats what I read. Forget the reason stated as well, but it was a typical manufacturer's excuse.


I wasn't saying there was anything such as a x or h-pipe type of design. I was stating that the two tubes actually are crossed over one another. The passenger exhaust exits on the driver side tipe and vise versa. 

For the new hood, it is not going to so to speak bring cold air in. It is going to allow hot air from the engine to vent or escape.


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## GTO TOO (Sep 10, 2004)

"Will the new hood with the scoops help bring cooler air into the engine compartment?"
No! They're blocked off.

"For the new hood, it is not going to so to speak bring cold air in. It is going to allow hot air from the engine to vent or escape."

Wrong again !! see above. If you were to unblock them, they are holes straight into the engine bay. I would hate to see what the engine would look like after driving in a rain storm or worse yet SNOW, with open hood scoops....The scoops are forward facing not rearward.


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## Guest (Oct 14, 2004)

Where you get that info. from. I read somewhere that it provides for engine ventilation.


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## GTO TOO (Sep 10, 2004)

I looked at the hood.


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

More air (cold) into and out of the engine at any RPM will get you more horsepower. As long as the ECU can keep up by keeping the mix correct(not to lean).
Cheep----- K&N filter with after cat exaust.

Bucks----- Hi-Flo cold air intake with supercharger and intercooler with fuel management and headers with complete dual 2 1/2" exaust.

With the money you can save on a 2004 before Nov 1st, do the bucks upgrade and blow the doors off any 2005 that might pull up.

A good supercharger kit should give you 100+ hp to the rear wheels.


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## westell (Oct 4, 2004)

SLP's ram air hood is functional, sealing to the oem air box.

they call it "ram air" but really it's more of a a plenum when compared to real ram air muscle cars of the 60's & 70's

now , this is good topic here, and it was and is also, on the SS owners forum.

for my 02 SS Camaro with the "oem" SLP ram air hood, it added 10 hp on paper.

but all the discussions, inlcuding that of SLP engineers, was that it only helped at high speeds as the fbod's were "bottom breathers" similar to the GTO

I noticed gains on the SS (seat of pants & dyno) by dremeling out some plastic that restricted air into the air box, K&N filter, and smoother air lid (MTI Clear) They were each small but still a gain. Also had exhaust cut out with electric power plate. with cutout open lost a little on the bottom, but gained more at the top. cutout was after the cats but before muffler


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## TexasRealtor (Oct 4, 2004)

GTO TOO said:


> "
> 
> Wrong again !! see above. If you were to unblock them, they are holes straight into the engine bay. I would hate to see what the engine would look like after driving in a rain storm ...
> 
> ...


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## westell (Oct 4, 2004)

don't know about classic ram / rain concern

SLP's have a couple drain holes at strategic locations


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## GasTiresandOil (Aug 2, 2004)

TexasRealtor said:


> GTO TOO said:
> 
> 
> > "
> ...


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## MaxHax (Oct 16, 2004)

The electric cut-out sounds like a good idea. I had a QTP electric cut-out on my 02 Camaro with a SS hood. 

I am new to the forum but not new to F-Bods and want to mod my 04 GTO.

Saying to sell the 04 and buy an 05 was joking right? That is silly of course.  I can't drive a totally stock car hehe never have been able too.

I'm sure there is a way to get some more power out of this car without going FI or N20 and I was looking at exhaust and air intakes first as I always do.

I haven't looked real closely into this yet but their has to be some restrictions in the intake and exhaus somewhere?

Also are there any ECU mod's out yet or does this ecu learn pretty well when you adjust the A/F? I had the Hypertech on my prior F-Bods and loved it but I guess it isn't made for this car.

I had an 01 Pontiac Firehawk that loved modifications though and it had lots of SLP stuff on it straight from the factory.

What did they change from the 04 to the 05 to get that extra power does anyone know? Anyways that is where I will start by reading the exhaust thread links posted (thanks) and lurking here and reading. 

Wanted to make my first post and say hi to everyone though.

Max from California.


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## 05GTO (Oct 6, 2004)

MaxHax said:


> What did they change from the 04 to the 05 to get that extra power does anyone know? Anyways that is where I will start by reading the exhaust thread links posted (thanks) and lurking here and reading.
> 
> Wanted to make my first post and say hi to everyone though.
> 
> Max from California.


Hello and welcome,

The 05 GTO offers a 400 hp 6.0 liter.

_*Modern Day Muscle Cars*_ offer a package to increase the HP on the 04 5.7. They have 410HP, 510HP and 585HP kits available for the 2004.


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## TexasRealtor (Oct 4, 2004)

MaxHax said:


> .
> 
> What did they change from the 04 to the 05 to get that extra power does anyone know? QUOTE]
> 
> The 2004 has a 5.7 LS1. The 2005 will have the new 6.0 LS2 (same as the vette).


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

Any Corvette engine or ECU upgrades should work for the GTO.


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## MaxHax (Oct 16, 2004)

This is all great info. Thanks for the HP increase link too I will read it.

I had mid length MAC headers on my FireHawk with an LS6 manifold (standard) and a manual cut-out that cost a whopping 50 bucks. The exhaust was 3 inches but by passed when the cut-out was open because I was running a 150 shot. It was a NOS 5177 kit with an MTI clear lid and it went to a descreened MAF with Thunder Racing ported MAF Ends. I also had a Hyperteh 160 thermostat and a Hypertech Power Programmer.

I bracket race thus the A4 choice plus I commute for a living at times in heavy Bay Area traffic. The 6.0 liter is a great thing but I hate the looking back and I should of waited routine.   

Truth is I got a $3500.00 rebate **AND** 2.9 percent finacing on a 5 year loan and they only had 2 GTO's in stock, black and yellow. Ever drive a car and say, "I must have this?" Well I loved it and I plan to make it fast. I will probably do the exhaust, some cams and internal N/A stuff. I'm not sold on after market headers for these LS1/LS6's in California unless they are equal lenth long tubes. Anything else is a waste of money to me and I have done this path many times. I am in no hurry though and I am forced to use a dial up while at work so it is slow reading for me. I will be lurking though and when I get home to my broadband I will be following others mods closely. I saw the exhaust pic in the link that was posted in this thread and it was SWEET! I also saw the Pro Charger box in the background hehe. If you check cardomain and search for the user sactownbooster (that's me) I have plenty of pics of my 9-10 pounds of boost on my Nissan 350Z I just sold. That car was a tuning nightmare but I ran consistant 12.2's and 12.3's after taking it to Technosquare and Edge racing and adding a 3000 stall torque converter and having it road tuned at the ECU level. The 350Z's were blowing engines left and right though because of timing. We had about 10 members lose their $6500.00 engines by jumping into FI w/o studying and I remember why I stuck with F-Bods hehe :cool . Anyways I think the exhaust has lots of bottle necks from what I have seen. Anyone have a sound clips of one of these after market setups that I can hear? Is there a way to get rid of any resonators without messing with the 4 02 sims? It looks like the thing has 4 cats and 2 mufflers? aRE THE 4 02 simms needed or can you just run the 2 after the main cats post headers and pre cat and delete the other 2 and do a cat back?

Anyways, thanks for the warm welcome, I am glad to have found this site so I can learn. I have been on LS1.com since 1999 but that site has just gotten too big. I have lots of pics of my SS and FireHawk there over the years.

When I get home I will post some more. Here is a couple of pics though plus I will take some of my GTO and show the progression as that as my car grows and gets faster. I just hot 1400 miles. Take care!

http://home.surewest.net/mailmax/pictures 2.htm

Time to update my page with some GTP pics!!!


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## vet652000 (Oct 15, 2004)

"Any Corvette engine or ECU upgrades should work for the GTO."

i don't think that you would want to try a programmer made for the vette in a GTO. the fuel maps/timing/shift points for auto among other things will all be different on the gto due to weight, areo differences. LS1 Edit of course would work for tuning the GTO, but as far as a predator/superchip/hypertech type programmer it will need to be GTO specific. mechanical mods would interchange, except for CAI and headers/exhaust.


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## MaxHax (Oct 16, 2004)

hearing about this new 6 litre with sportier hood is depressing. I need to hook my car up. What website are people here using for their mods since the GTO is sort of unique parts wise?


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## MaxHax (Oct 16, 2004)

Now I remember why I love F-Bods.

http://www.thunderracing.com/catalog/?action=vehicle&vid=13

The prices are a 1/3 of what I paid to mod my previuos car. 

Now it's time to play. Hehe, they even have a 90mm throttle body and FIPK already, that an an exhaust will be a good start. 

Can't wait to bring this car alive!


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