# The engine computer



## LarryM (Aug 17, 2004)

Talked to the sales guy at the Pontiac dealer, who confirmed my suspiction - the computer monitors how you drive and adjust the engine performance accordingly.

You see, my GTO is my everyday, to-and-from work car. For me, this means about a 30 minute crawl each way. (Ugh) Oh, there's an occasional time where I get to unleash a few ponies, but much more a droop along with the crowd.

So now on the computer is getting all this data saying "Oh, he like to drive nice and slow, easy does it..." which is alright while I'm in the mist of this, but how do I tell the car, "Okay, its Friday night, we're going out to terroize the race hondas!" ?

The sales guy suggested calling the 800-number roadside assistance and asking to talk to an engineer.... I can here the conversation now: "Um, Ya... Hi, this is Roadside Assistance? Ya well, I'm about to get my doors blown off by this Mustang next to me at the stoplight unless you can tell me how to reset the computer."

Anybody know how many "data points" the computer keeps? If I do X-number of WOT (Wide Open Throttle) take offs, will that give the computer the idea that I'm some mad man that it better wake up and get out of slug-mode?

---Larry


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## rock421 (Aug 7, 2004)

Bill Reid might be your man for this one. I will throw out a SWAG anyhow. The sales person at the dealership isn't a technician. Most of the factory technicians I have dealt with over the past ten years here at the dealership don't care how your car performs at WOT. There are some excellent people here in our service department, but performance is not their usually not their game. 
I could be way off here, but the car does learn as it is driven. What it learns at a low percentage of throttle opening with a given manifold pressure and MAF reading is only going to adjust the low speed or light throttle part of the map. I can't see that a WOT high load map could be compromised from low speed info. Heck I don't know, I'm just a parts guy!
I do have a buddy with a 99 Firebird (4L60E). He used to drive 40 miles round trip to work and back every day. He raced the car almost every Saturday night and we never noticed any kind of performance issues.
I'm sure that someone will post a reply and set things straight.


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## rock421 (Aug 7, 2004)

I just talked to our tune up and driveability tech. He referred to it as "adaptive memory". He felt that the main purpose was to adjust shift points and shift firmness to suit driving conditions. He was not sure of the time frame needed for the ECU to learn or change, but he did say that at WOT the ECU falls back to a fixed timing and fuel map to give you max power regardless of what the car has learned up to that point. 
I still think that someone with some chassis dyno experience and something like the LS1 edit program could tell us for sure.

Brian


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## LarryM (Aug 17, 2004)

Brian,

Hey, thanks man. You're right, the sales guy isn't technical, but said he did consult a tech. Now, not sure if that meant the order writer from the service dept, or someone that might actually know. He has, on other occasions, gotten information from someone who's title I can't remember now (the memory is the 2nd thing to go... I forget what the 1st is...), but it did seem to be a good source.

A relatively easy thing that Grand National users did was simply disconnect the negative side of the battery, count to 10, then re-connect. Easy to do on race day. That allegedly set things back to their starting point.

It would be interesting to here exactly what the ECU controls when it "learns" and how much variance it is allowed.

---Larry


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## LarryM (Aug 17, 2004)

Drat - meant to ask... what is "shift firmness"? What does that mean?


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## rock421 (Aug 7, 2004)

Shift firmness is just how hard or soft the trans shifts. On your GN, you had a 200-4R trans that was controlled by a TV (throttle vave) cable hooked to your throttle body. It was a little bit different than the old "kickdown" cable from the 70's. The TV cable was constantly telling the trans what the throttle position was. A combination of that and the trans governor speed told the trans when AND how hard to shift. This was accomplished by raising or lowering the line pressure within the trans. Light throttle and low speed would give you an early soft shift. When you go to a greater throttle opening and/or increase the RPM in a lower gear,the trans would shift later and harder/firmer.
On your Goat, everything is handled with electronics. No more external cable or mechanical governor. It uses the throttle position sensor and vehicle speed sensor to calcutale engine load, then uses the pressure control solenoid and multiple shift solenoids on the valve body to control shift "quality". It's still just a matter of changing and applying line pressure to hit the clutch packs harder or softer, sooner or later. 
Sorry for the ramble session.

Brian


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## LarryM (Aug 17, 2004)

Oh no, ramble on man! I'm just a computer geek that likes fast cars, but knows only a few details about such workings. I had no idea that "firmness" was something that was controlable. --thanks!!!!

Larry


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## GTO TOO (Sep 10, 2004)

"Adaptablity" is NOT preformance "learning". The ECM does not "remember "how you drive nor does it effect preformance as you know it !!!
The adapt leaning in the ECM software is there to make all vehicles preform the same with regard to shift "firmness", and is in there to account for production variation. The length of the actual shift is measured and internal shift pressures will be "learned" into memory. ( to yeild a given shift time at a given ERPM )The adaptablity is not related to a shift pattern, " how and where the shifts occur with regard to RPM" ( that will remain as programed ) but to make every vehicle "feel" the same for the same throttle input vs. a given ERPM and shift. Hope that helps. I'm not sure I can elaborate further. I know how it works. I will jump in and try to help with technical issues in the future. But what is said on a public forum ( for Me ) will have limitations.


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## cr125 (Sep 12, 2004)

its adaptive fuel strategy. if your abuot to go out terorizing hondas just start giving it hell more often before you actually get to terorizing them. it takes a few miles to lean the new driving style. most late model cars have this. it does render performace but not really enough that you will be able to tell.


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## GTO TOO (Sep 10, 2004)

CR125,
The first questions were with regard to shift learning or transmission adapt learning. (Shift point do not adapt nor learn) 
What is "learned" in the transmission is line pressures as they releat to shift times, measured by the ECM,and they do not change the shift points vs. Throttle. 
Secondly, fuel "learning" does not effect WOT. Fuel learning is feedback control from the O2 sensor to keep the engine at soich during "closed-loop" fuel control. While there is some effect from the learned " adapt" fuel to wide open A/F ratio. ( how you drive does not change what is learned as the fuel map is adapted vs. speed and load. And unles you have NEVER run at a particular speed and load the default value would apply. Other wise the last time that speed and load where encountered the "adapt" is already in memory.It is not ONE memory but many seperate memories that cover the entire engine operating RPM and load range. If you drive easy and did not "learn" a particular speed and load for some length of time, that does not change the last value that was learned. After the initial "learn" of a specific hardware set the adapt values in memory will only change slightly, or until a very different fuel chemistry is used. ie. Calif. Phase II or winter vs. summer blend) The WOT A/F and some other operating modes are NOT closed loop. They are open loop fueling. So for all intents and purposes how you drive and how the fuel adapts "learn" does not effect wide open throttle. The only adapt "learning" that does effect performance, is the knock control portion of the spark control. That is a complex system, however, as long as you have a high enough octane fuel to avoid any detonation, you will have maximum spark. ( Once the system "senses" NO Detonation it does not add more spark if you increase the octane even higher.Above the recommended 92 octane. The Max. spark is set for 92 octane fuel. And any gains that might be realized form a higher octane are moot without a corisponding increase in spark.)
So I stand by my statemant, how you last drove your vehicle does not change the performance with regard to shift speeds or Wide Open A/F ratio.
If you hammer it when it's hot hard enough to start getting detonation, you will have less spark until the knock system "learns" back to the max. spark values in the ECM. But driving "easy" all day, as was the original question" does not need to be "unlearned".


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## lisatw151 (Sep 8, 2004)

okay...y'all have impressed the hell outta me with your technical jargon, but i haven't learned a thing. my goat is my everyday, to work and back and grocery store, vehicle. i 'get on it' every once in a while, but nothing spectacular. tell me in lay terms what it is that you just said.... does it mean that since i rarely get into 'race mode', that the next time some punk ass kid in a rice burner pulls up next to me, i've got less chance to beat him cuz i drive like a girl?


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## AlaskaGTO (Aug 29, 2004)

Nope, I think he means you can still make him spill his soy sauce.


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## lisatw151 (Sep 8, 2004)

LOL....good! Cuz nothing makes me happier than to pull up next to some tuned out little honda piece-a-crap and see them do a double take. after that second look, they won't even look in my general direction...LOL


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## Tuxedo Mask (Sep 13, 2004)

Hehehehe. Good one. i really dont like those rice rockets. They are the worst things since "clear" coke.


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## LarryM (Aug 17, 2004)

I thought it was just Pepsi that was clear for a while....

What cracks me up about those rice burners is the HUGE wings the put on the trunks... Someone should at least point out to them that the direction they have them pointed is counter productive to a front wheel drive car.

---Larry


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## Tuxedo Mask (Sep 13, 2004)

Oh yeah. You are right, Larry. It was clear pepsi. The coke scandal was with the "new" coke. Dont you just love the 90's??


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## GTO TOO (Sep 10, 2004)

Lisatw151,
In simple terms; as long as you've filled with 92 octane fuel, it will function the same every time , even if you had been driving "like you stole it"!!!!
When you hit the loud pedal it's ready !!!!!!


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## George8211 (Sep 21, 2004)

Don't be too easily impressed until you know that the information presented can be backed up with data from a realiable source. As some members here do posting AND provide supportive proff of their claim... you all will learn that they know what they are talking about.


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## George8211 (Sep 21, 2004)

BTW.... PCM via OBD11 port; data point tracking, does allow for adaptive learning of the transmission RPM shift points and firmness (line pressure). The link below will take you to a site by Vericom Computers that shows all the data points that are captured by your OBD11 in your car. The computer will use this information to capture trouble codes and learn the optimun way to manage engine systems.

http://www.vericomcomputers.com/OBDII enhanced GM.htm

Auto Tap is one company that creates hardware and software that will allow you to read PCM data using the OBD11 diagnostics.

http://www.autotap.com/

LS Edit is an example of software that can be used to alter ranges of certain management functions by changing numeric data in the PCM tables. You guys & gals will soon learn the tricks of how to squeeze extra HP buy tuning your computer... and maybe get faster 1/4 mile times by shortening your shift duration (for autos) good for about a 1/10 of a second. Reducing the amount of time it takes for the timing to recover from knock retard... ect

http://forums.corvetteforum.com/archive/index.php/t-765035.html


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## GlennH (Sep 22, 2004)

What about the PCMIII from SLP or the Predator that are supposed to be able to reprogram your computer. Do they actually work or can you really screw stuff up by using them? Also, if you reset to factory defaults before taking your car to the service department, can they tell what you did and do you run the risk of voiding your factory warranty?

I just purchased my GTO, and would like to get more power out of it (as if it really needed it). Are there other ways to increase 0-60 that are both safe for the car and not run the risk of voiding the warranty?


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## GTO TOO (Sep 10, 2004)

GEORGE says "Don't be too easily impressed until you know that the information presented can be backed up with data from a realiable source. As some members here do posting AND provide supportive proff of their claim... you all will learn that they know what they are talking about."

George, just because you read something about OBD II does not mean you know how the ECM "learns". OBD II outputs are only one portion of the ECM software that is mandated by the government. Genric scan tools are required to be able to read certain ECM data from ANY manufacturer !!! Those outputs and their are legislated.

You also stated
"data point tracking, does allow for adaptive learning of the transmission RPM shift points and firmness (line pressure). "
I did not say the OBD II data point tracking changed line pressure.
I told you how in a generic sense the ECM "learns and WHAT it learns"

However, the actual control software within a given ECM uses many other inputs and not related to OBD II mandated diagnostic tools and functions. Shift firnness as related to line pressure is learned. As are the other items I mentioned. I have said I will help with a few facts. But if you wish to work on opinion I will be happy to stay out of the discussion.


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## George8211 (Sep 21, 2004)

> GTO TOO The first questions were with regard to shift learning or transmission adapt learning. (Shift point do not adapt nor learn)
> What is "learned" in the transmission is line pressures as they releat to shift times, measured by the ECM,and they *do not change the shift points* vs. Throttle.


As you can see in my posting... shift points do change through learning.... I'm simply challenging your statement... if I'm wrong show me. Show me the facts that you claim to have... that's not asking for much. This is a learning forum.

Also I asked you some question in a post and you did not answer them. I was asking if you could clarify and expand on some of your statements. If you don't know the answers to your own post... it's ok, but I would hope you do. I'm not asking you to not post .... I'm asking if your going to make statements... do it so we can learn from it, versus talking over many peoples level of understanding.


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## George8211 (Sep 21, 2004)

lisatw151 said:


> okay...y'all have impressed the hell outta me with your technical jargon, but i haven't learned a thing. .... tell me in lay terms what it is that you just said....


GTO TOO This is an example of what I'm referring to. Here's a member that is egar to learn and understand her GTO... But you are going right over her head (and others) with your information... When she stated that she wanted to learn ... you ignored her post and just started running on about some thing that few people understood.

So what's up?? Are you just being rude to some of us... or do you just perfer talk over everyone's level of understanding so everyone knows less than you. If you go on the Corvette Forum... you will see that everyone shares information and it has become the global source for every thing Corvette. This forum has the same potential to be the Global Source for everything GTO... and you can be a part of that. I hope you will. People will want to be here and want to read your post (and others) if they are treated as equals and with respect they will stay here.


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## lisatw151 (Sep 8, 2004)

Thanks George. My eyes kinda glaze over when I start reading some of this stuff. LOL


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## George8211 (Sep 21, 2004)

GlennH said:


> What about the PCMIII from SLP or the Predator that are supposed to be able to reprogram your computer. Do they actually work or can you really screw stuff up by using them?


Yes the software you mention have simular capibilities as Auto Tap, like GTO TOO stated in one of his post... The access to this data has been made public to allow competing companies to develop software to access this data. Yes, they do work... you can change lots of things.... and yes, you can screw stuff up if you change values into unsafe territory. If you know what you are doing... you can do some cool stuff. I had a local tuner do my changes... In what is referred to as a "Mini Tune".

Forums like this one here... will be able to help do some of these changes as experience is gained and then shared about the GTO. The more people that get ID's here... the more knowledge will be available.



> Also, if you reset to factory defaults before taking your car to the service department, can they tell what you did and do you run the risk of voiding your factory warranty?


You always have to be careful with what is changed. If you have a warrenty claim that has damage do to a PCM change... it could cost you. In general they will not check for changes. But often re-flash the PCM if codes are triggered for some kind of problem. They also re-flash it to provide the lasted version of data. If they do this.. you will have to make your changes again.




> I just purchased my GTO, and would like to get more power out of it (as if it really needed it). Are there other ways to increase 0-60 that are both safe for the car and not run the risk of voiding the warranty?


Personally I don't really know the answer to this. It's kinda on a part by part basis.. and it depends on who services your car... and what kinda of claims you have. If you change Transmission settings and your power window fails... GM will cover the window. Now if something happens to the transmission... hhuummm.

Hopefully... We can get some turners to get ID's and share some info and maybe some Pontiac mechanics & service managers... Maybe even some GM GTO engineers. :cheers


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## lisatw151 (Sep 8, 2004)

So George... what kind of changes are made in a so-called "mini-tune"?


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## GTO TOO (Sep 10, 2004)

Goerge I promise this will be may last post. Sorry if the technical explaination was OVER someones level of understanding. Last time I looked I was still free to answer or not as I see fit. I stated I would try to help with the facts not opinions when I knew the answer. As i don't read these threads 24/7 I'm also sorry if I didn't answer your question FAST ENOUGH.Patience is a virtue.
One of your questions seemed more in the vein of arguement than truely asking a question, form the tone of some of your responses that is how I took it. As you wrote "Don't be too easily impressed until you know that the information presented can be backed up with data from a realiable source. As some members here do posting AND provide supportive proff of their claim... you all will learn that they know what they are talking about."

The smartest guys I know, know how to ask questions and get the answers to what they have asked. ( Ive never watched any of them argue the facts, about that which they didn't know before the answer was given ) Badgering the witness only works on Perry Mason. 


I will give you an example of how these threads and forums work. I had a friend that was the Program manager for a large software supplier at a major motorcycle manufacturuer. He jump on one of the BIKER threads and tried to tell some of the guys what they might screw up with some of the mods they were doing. He wasn't altruistic you see he knew when they screwed it up they would blame the ECM software. He had guys telling him how things worked. He did not tell them he was the program manager because if he had anything he said could have been construded as the manufacturer approving some after market mod. And to tell someone what you do automaticlly means approvals from the manufacturer would need it be obtained before any answer was given. I watched the same biker thread rip a piston designer that told them who he was and they still tried to tell him why a piston was designed the way it was. In the end it's not worth the effort to argue, as he knew already HOW IT WORKED and WHY. HE was merely trying to help, HE WAS NOT THE ONE asking ( as he did know the answer ) he was just trying to explain.

I am not looking to argue and bicker over how something works if someone has an opinion great, they may be right. Or they may be wrong. That is how opinion work. However, the fact of how something works is not open for debate. As you didn't like the few explainations I've attempted to supply
I will leave the group to discuss "opinions." That's alway more enlightening than a few facts.


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## George8211 (Sep 21, 2004)

Please don't leave 


(you got private message)


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## MaxHax (Oct 16, 2004)

It sounds like the GTO has open and closed loop.

One thing we used to do at the track if a new mod didn't show gains is pull two ECU/ECM fuses, instant clearing and reset. Then go romp for about 15 minutes. It should reset your A/F and spark.

These computers are really starting to suck. Make it fast enough and you can stomp these Stangs anyway! We have 5.7, 6.0 litres they have 4.6  learned or unlearned just romp it once a week and I would think you should be OK.


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## westell (Oct 4, 2004)

good thread :cheers 

now, i'm heading over to Motorsports Tech., Inc, (MTI) here in Houston to get dynoed $75, two pulls, and they offer PCM tuning $500


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## MaxHax (Oct 16, 2004)

Cool let us know how it works out, I plan on needing some tuning too.

P.S. I certainly hope that no one would leave here or quit posting this is a great board! Disagreements come and go on al boards but it's the members that make the forum as a whole!

BTW,

Closed Loop on my Nissan was hard coded and could not be changed. Open loop was where the tuning usually occured with timing, A/F etc is this the same with our GTO's?

Most WOT runs resulted in open loop, pretty much anything after 4k rpms?


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## kevracer (Sep 27, 2004)

My Cadillac Catera had adaptive memory shifter; it seemed to adjust the firmness of the shifts over time, but I never had any performance issues.


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## GTO TOO (Sep 10, 2004)

*Scan tools*

Ok here's a test:
On the following list; Which are inputs which are outputs which are RAM memory locations? Bonus question, how do the adapts work to change the "SHIFT Schedule?". 
Here's another hint, look at the last few entries on the list and explain why they would be included for a GTO on the "Genric Scantool software".

Enhanced Parameters for GM*


1-2 Adapt High Cell
1-2 Adapt Low Cell
1-2 Shift Desired WOT RPM
1-2 Shift Time
1-2 Shift Time Error
1-2 Shift WOT RPM Adapt
2-1 Shift Time
2-3 Adapt High Cell
2-3 Adapt Low Cell
2-3 Shift Time
2-3 Shift Time Error
2-3 Solenoid Circuit Status
3-2 Shift Time
3-4 Adapt High Cell
3-4 Adapt Low Cell
3-4 Shift Time
3-4 Shift Time Error
4-3 Shift Time
A/C Evap Temp
A/C Highside Temperature
EGR Desired Position
EGR Duty Cycle
EGR pintle position


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## asteng88 (Aug 26, 2004)

*Understanding*

Listen Guys, I'm With George. I have a PhD in Dye Laser Physics and I can't understand what the heck GTO TOO is talking about sometimes.
GTO TOO, just tone it down a bit. If I started talking laser physics to you you at a level I can understand I am sure you wouldn't have a clue at the first acronym.
Best Quote I ever heard was if you can't explain it then you don't really understand yourself.

So, for the benefit of us non-GTO Teccys, would someone just post a laymans summary please.

Thanks and I think this forum could be a great learning tool for people like me.

Thanks

Andrew


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## GTO TOO (Sep 10, 2004)

Andrew,
"Best Quote I ever heard was if you can't explain it then you don't really understand yourself." I doubt if an engine overhaul mechanic could explain how an engine works to a eskimo that had never seen a car, but it doesn't mean the mechanic is ignorant. It may mean the eskimo doesn't know what an engine is ! My offer stands, I'll be happy to quit wasting time trying to explain if it is too technical. You're, as always free to guess how it works..

The list above was on the link provided by GEORGE to prove a point. If you do not know what the list means then a scantool is not for YOU. It does not however reflect my understanding or lack thereof of the subject matter, just your unfamiliarity with scantool verbage.

The list is a list of generic readouts on A scantool. All ECM's ( the box that runs the engine ) has various functions. Some of those names listed above are sensor inputs into the ECM ( computer ) some are outputs from the computer ( ECM ) and some are stored RAM ( names and words in a computers storeage memory )
If as George asserts they prove anything, the first thing one would need to know is how they are processed by the ECM. MY POINT which I will jump to is this. The Generic scantool has place holders for EGR ( Exhaust gas recirculation, where an engine is forced to inhale some quanity of it's own exhasut to cool combustion and lower NOX emmissions ). OUR GTO does not have EGR. But it's on the list. What does the list prove. ( go check Geogre's post's link if you wish to see the whole list !!) The list proves nothing as only some may apply to one application and not others. If you don't know how it works or understand the terms there are places to learn. If we all input ideas at the level of the lowest level of understanding, someone will be writing a dictionary. If I wished to understand DYE LASER physics I would try to learn what I didn't understand, I would not question what you knew of the subject.
If we were to talk one on one that is a different story, but THIS IS A technical discussion board I may have wrongly assumed most wished a technical answer.


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## mike_21_ohio2004 (Nov 8, 2004)

this is the thing guys there is no point to argue if u dont wanna read what he says then skip it. all i wanna know is what options i have to make my 04 gto faster. i want a gto that no one can touch and money is no issue. im just not much on knowing about new cars. i want ideals on wat bolt ons and motor mods i can do to boost my power. if u have any suggestions send me a private message thank u


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## xom (Nov 11, 2004)

AlaskaGTO said:


> Nope, I think he means you can still make him spill his soy sauce.


hmmmm.....not so cool to say. 
And as a current WRX owner I can safely say that I can eat "goats" for lunch.
Straight line or on the track.


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## kevracer (Sep 27, 2004)

_And as a current WRX owner I can safely say that I can eat "goats" for lunch.
Straight line or on the track_.

Sounds like a challenge.........


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## xom (Nov 11, 2004)

kevracer said:


> _And as a current WRX owner I can safely say that I can eat "goats" for lunch.
> Straight line or on the track_.
> 
> Sounds like a challenge.........



Not a challenge, a fact. 300HP 3,000 pound AWD car VS a 350HP 3,700 pound RWD car. Pretty simple math there.
I'm just tired of people spewing ricer this and ricer that. Yeah, there are cars out there with huge wings and primer colored airdams and fake carbon fiber hoods. But that still doesn't change the fact that there are also extremely well built and "tuned" Japanese cars out there that would destroy a stock GTO in any test.
Of I wouldn't be on this forum if I wasn't intersted in this car.


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## GTO TOO (Sep 10, 2004)

I drove a WRX Sti. It's fast. It is not a well refined car. It is an econo car with a lot of horsepower. I took it out on a track and at 135 it is not nearly as stable as a GTO. Nice seats, great tires, and econo box body. I'll take the rest of the package and vote GTO.


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