Thread: Order of mods and feedback requested

Originally Posted by diesan04

Ok- here is my first post, I have done alot of individual reasearch but am looking to 'put the plan together'

Working on an '04 GTP CompG (not many of those around or am I way wrong?) that is stock and have a few things "in mind" but looking for some decsion assitance. In short- what 'order' is best to do mods? Cosmetics (debadge) and other cosmetics are easy enough to decide, so I am really talking about mechanical.

Here is what I have in mind- please let me know if I am way off base or have a good start. Also, my intent is to build out to a faster ride that is visibly different but wont scare off the Stangs and STIs or any of the sewing machine rides.


Before anything- need new brakes. Ideas are most welcome here as I am all over the place on thoughts.

Now, as far as mods-

1) CAI (Thrasher, K&N or Wiz- prlly gonna go Wiz from my 'research')- with a question on the oil from the filters potentially casuing an issue. Unless the "new one" I see here in forums is 'good'.

2) Smaller pulley, PCM, cooler plugs, and "the other stuff" needed to keep the motor clean running

3) new struts and lower it a bit (reccomendations on height and suggs for solution here?)

4) Headers and exhaust

5) New cam

As an aside, I have been looking at the "performance packages" from 3800performance.com. If anyone has gone this route, what are your results?

Yeah, alot here- but I have not modded a car since my last sleeper which was a '76 Grand Prix with a 455 HD. (anyone even remember boring an engine or Holly double pumpers? )

Thanks to all- I will say I have looked at a number of posts on each of these ideas but cannot really get a good clean handle on 'order'. I also udnerstand that there is a great deal of personal preference, so I will keep that in mind too.

.5)Brakes - I would recommend you to look into the F-Body brakes. ZZP, WBodystore, etc sell kits. There are also some good writeups on how to piece them together yourself. A lot of 97-03 guys do this. Not sure about the 04+ guys. But I would imagine it would work just as well.

1)CAI - Personally, I made myself a cheap DIY CAI using ABS pipe. Others have used PVC pipe. These seem to work very well for the money spent on them (about $50). You can spend a lot more money, and only get a little more performance. I always tend to go the cheap, but effective.

2)For a pulley, I would get an MPS. A little more money, but you will thank me later. Don't drop much in pulley size until you get all your mods straighten out. Then start to drop pulley sizes. Dropping pulley sizes prematurely will only complicate things.

Plugs all depend on the level of mods you are going. But from the sounds of things Autolite 104s will work very well. Other things include a tuneup which is always recommended. Wires, fuel filter, trans fluid & filter, shift kit, etc.

As for a PCM, personally I would suggest getting a tuner. And make that your first mod. Learn the tuner. Learn how to use it. A PCM will cost you about $100-$200 depending on how good you want it tuned. But that is only good for your current level of mods. Change something, and your tune is thrown off, so you are stuck with a bad tune which sucks, or pay $100-$200 again to have it retuned. If you spend $500-$600, you can tune your car the way you want it. If you don't like something, you have the power to change it. You can have 100 different tunes for daily driving, street racing, track days, economy, etc, etc, etc. Not to mention any mods you do, you can simply retune it yourself. By far the best mod I ever bought and should have been the first.

3) Not much recommendation from me. Don't know much about suspension, especially 04+ stuff.

4)Headers - All depends on how much you are looking to spend and how good of quality. You can get stainless headers off ebay, which work fine, but quality sucks, for $300. Or, you can get stainless headers from ZZP for $800, and have excellent quality. Personally, if I went with headers, I again would go towards the cheap end. But I am also cheap.

For the rest of the exhaust, I personally went all custom. I bought Borla Pro XS mufflers, a high flow cat, and had a local shop weld up my SS exhaust. If you are looking for a good aftermarket bolt in exhaust, I would look at ZZP, Borla, or Magnaflow. Listen to some sound clips and find what you like. Personally, I like my Borla exhaust. But that is all subjective.

5) Cam - I don't have much experience with cams. I will let someone chime in here.

As for the performance packages, I personally wouldn't go with them. I would get a tuner first. Learn to use it. Then piece by piece mod the car. And after every mod, retune. This will teach you what each mod does and how it affects how your car drives. Then, when something goes wrong down the road, you have a better understanding of how everything works and what might possibly be wrong. If you just buy a bunch of parts, install them, or have them installed, you don't learn much, and don't know what is wrong when something breaks. I find it much more fun to learn as I go.

Hope this has helped.

our stock comp g suspension is problew better than the cheaper struts, they are just factory replacements. you might have to get the exspensive ones for them to be any better. personally i would just get new comp g struts.

There is a rough guess that there are appx. 30-35k GTP Comp G's out there. But some are piled up, up in smoke or up a creek. So who knows?! But you did pick the better year.

NOTE: The correct mind-set you need is how fast do you want to go and how much are you willing to pay. Figure both of those out before purchasing anything and get yourself in a hole with a pile of debt or a pile of a car.

1) Build your own air intake. ABS, PVC, SS tube, whatever. If you are trying to go for overall performance look around some more on here or on other GP sites for some ideas on what to do. I bought an SLP CAI, but the only reason was because I was going for something discrete. Just make sure you put it in the FW and block off the hole.

2a) If you really want to run one. A 3.6" is what I would start with. It's a .2" drop over stock (3.8"). General rule I have seen with the Gen V charger is about a pound of boost per 1/10" in. drop in pulley size. Given this changes with air temp, humidity and sea level o/c. I would go after freeing up some exhaust restrictions first.(See below)

2b) Agreed 100% if you want to tune. Get a HP Tuner or something of the sort. There is nothing more benificial than being able to tune your car immed after installing another mod. Consider this your most important purchase for continued modding.

2c)Plug wise, I would only drop what you need to. One or two heat ranges depending on what type of t*start you are using etc. If you drop to far you will have a problem where the plug will not self-clean because it is not warm enough and will end up fouling itself out. You can always drop more as you go with more mods. And besides, it's $10 to for a new pair. So it is not going to kill to run what is proper for your current set-up.

3) Stick with another set-up of Comp G struts. This is best set-up for these cars. I have yet to see a GP that handled better with a set-up w/ KYB struts.
Ride height to me is a matter of preference and how much of the pick-up truck look you want to lose. There is no critical height or spring rate that will let you 10+ mph faster in the corner than the next one. Lower it 1-1.5 in, get some STB and be done with it.

4) Definitely comes down to cash. There are plenty of options out there. You could go ported factory manifolds. A Plog from ZZP.(Get the front only). Or go with the headers. If you do anything at all, change the front manifold out and replace the down pipe. Those two things together are as close as you will get to hears without shelling $800 you will see noticable gains. Exhaust sound on is all subject to the ears of the beholder. For the lil bit extra, run a 3" back instead of stock 2.5" Like previously rec. check out some clips on youtube, etc. If you go custom, most people will warn you to keep a resonator in for fear of the dreaded "drone".

5) If you don't want to put the labor into a cam swap. You could go rocker arms and springs for a similar effect (don't read as same effect.) Cam would be one of the last things I would get after I was done modding up everything else and get one made for exactly what you're running.

*6) Depending on your extreme that you are going for, I would include looking into building up your tranny as well as it will be one of the first things to go if and when something goes.

Ha, that was my 0.2 cents on it... ok may be a $1's worth there...

I switched the basics on mine and am content with it. My order for a new Camaro just went in yesterday sooo... that's where I am at.

Originally Posted by diesan04

Before anything- need new brakes. Ideas are most welcome here as I am all over the place on thoughts.

Now, as far as mods-

1) CAI (Thrasher, K&N or Wiz- prlly gonna go Wiz from my 'research')- with a question on the oil from the filters potentially casuing an issue. Unless the "new one" I see here in forums is 'good'.

2) Smaller pulley, PCM, cooler plugs, and "the other stuff" needed to keep the motor clean running

3) new struts and lower it a bit (reccomendations on height and suggs for solution here?)

4) Headers and exhaust

5) New cam

As an aside, I have been looking at the "performance packages" from 3800performance.com. If anyone has gone this route, what are your results?

Yeah, alot here- but I have not modded a car since my last sleeper which was a '76 Grand Prix with a 455 HD. (anyone even remember boring an engine or Holly double pumpers? )

Thanks to all- I will say I have looked at a number of posts on each of these ideas but cannot really get a good clean handle on 'order'. I also udnerstand that there is a great deal of personal preference, so I will keep that in mind too.

a cheap upgrade is the 12" brakes (actually 11.9") from other GM vehicles. its what i did and they work great. you just need the caliper brackets and rotors.

intake: make your own. it will be the cheapest and best solution you have to any of this. all of the intakes on the market are THE biggest rip off you can find.

pully/etc: no. not yet. you have a series III (l32) which will knock a lot if you think you want to drop a pulley on it. do not do this without other stuff beforehand.

struts/springs: get vogtlands if you want anything with a decent ride. all the rest will drop it too far to keep a smooth ride. struts...if any, get AGX's, made for lowering applications.

headers: you have many choices. if youre handy with a set of wrenches, get the cheapest set you can find (SSAC on ebay probably). if you dont know jack, dont get headers because you will not have a fun time installing them. instead, get a powerlog and a 3" downpipe.

cam: if you get this far and think you can tackle it, it really depends on what you want as far as driveability, power range, etc. tell us what you want and we can recommend one to you. most people go for the XP, which is basically the biggest you can go with stock heads. i am not a sheep, therefore i would not recommend this cam, but that is my opinion.



BEFORE YOU THINK ANY OF THIS POST MATTERS...tell us what you want out of the car before we can give you a better idea of what you need to get.

also, an intercooler is probably the best thing you can possibly put on these cars. think about getting one of those instead of a cam, seriously.

Cams...OH I KNOW So I'll chime my happy ass in on this one lol

Personally, I went with the Comp Cams XP-HOT cam. It is the most aggressive cam you can have with stock heads and I love it. Not enough to kill the daily drive to work (and yes it is by no means a garage queen, it has seen snow, rain and all that jazz)

Intense-Racing sells I believe 4 different cam grinds from their Stage 1 all the way to their Stage 4 Nitrous/Blower cam that requires a crazy build to support it.

ZZ Performance sells the Comp Cams brand camshafts and they seem to know a quite a lot about them. If you are getting a cam you might as well think about you options. If you don't want to hurt mpg, then I say go for the 1.9:1 Ratio Roller Rockers. They are basically the performance of a cam without the loss of drivability. But don't get me wrong there either. It is mostly based on opinion and self-preference. I don't mind sitting at a stop light and feeling like the car is gonna die out on me and then spurs back to life It's pretty menacing to say the least. And you are still going to see a little more performance out of a cam. And also keep in mind that you can't do both cam and rockers due to the lift.

And like you had stated. If I were to start over (keep in mind I drive a '03), but if you are going with a cam then you might as well start with headers. They kill out most of the exhaust mods GTP owners would do (Downpipe, U-Bend Delete, Cat Delete, etc.). Then I would say, Some for of CAI/FWI, 180* T-Stat, Poly Mounts, PCM (preferably a DHP, which 3800performance sells), either Autolite 104's or NGK TR55 (before cam) or Autolite 103's or NGK TR6's (post cam swap). Then after all that I say buy a M.P.S. (Modular Pulley System) and drop to a 3.5"/3.4" but be sure to have a tool to scan for KR. I never did and wish I had. I blew the crap out of my car with just a 3.4" pulley...so it is all based on the car too...everyone is different.

With a cam installed (keep in mind you also would need a tune with the cam as a stock or mail order PCM won't cut it anymore) you might also need to spring for stronger valve springs, a larger Throttle Body, such as a Northstar or LS1...or even ZZP's 78mm Billet TB (even my ported L67 TB was choking out my XP Cam), 85mm/LQ4 MAF, and injectors. After all is said and done you could probably get away with a 3.2" pulley with no knock depending on conditions and the tune. I ran the 3.2" daily with no KR and occasionally I would drop to the 3.1". It sure would pull hard at first but then I would see KR up to 2.1* so I quit with that on pump gas...

All in all man, even you say personal preference...and if you were to go with a cam...the XP is probably the best mod for the money IMO. Like I said to benfit from it you will need headers, a custom tune, larger throttle body, probably a 3.25"/3.2"/3.1" MPS Pulley...I'll post a vid of my car once it gets done downloading

btw man here is the video of my cam start-up...still has the vacuum leak in the vid and we actually found that out to be the T-fitting on the Lower Intake Manifold.

YouTube - XP Cam Start-Up

if youre just looking for a peppy, reliable car to drive, headers and cam are not needed. get rockers and plog/downpipe, an intercooler, drop pullies, and get a tune on it. it will be fast as crap compared to how it is stock with just this setup.

otherwise if you want something fast (and possibly unreliable) that you wont want to drive everyday look into a cam, headers, and an intercooler. heads? thats up to you.


you can find a lot of this stuff used for a lot cheaper than brand new.

I drive my cammed/headers GTP everyday. Don't know where the unreliability comes from unless you don't know how to install something...

Have yet to have a problem with it and I ain't nice to it either.

not saying that it isnt reliable if you take care of it, but my rockered car is more "streetable".

Uh, not before mine gets left at your house lol

Just be sure he doesn't do the 115 mph spark cut off mod to your PCM LMAO!!!

hahaha lets hope not.... Anything going on this weekend any meets of the sort?

Ummm...tearing a GTP down to get ready for a tranny install...other than that nothing. If the weather holds there might be a track meet Sunday @ KCIR at noon

Alright cool, keep me posted please...

If you want a good filter that doesnt use oil, but an Amsoil Eau4090. Thats the one you needs. 4" x 9" cone.

Originally Posted by GTPRiley

Alright cool, keep me posted please...

As long as it is 40* by noon I'll be there

Personally...I'd go with a K&N filter...always tried and true, just my 2 cents though...

I like my AEM filter, that oil on the K&N always clogged my mass air flow on my previous cars.