Howdy fellas, names mitch.
I got a 08 gxp and its stock, with the exception of a K&N filter.
im not looking to go as far as a turbo, but i would like to do some small add ons to get better power out of it.
MSD, a programmer, mabey some over sized injectors....
i was told that LS4 and ls7 are compatable. while i have a hard time beliving this, its jsut what i was told?????
oh and no im not rich so lets keep that in mind shall we.

 

Try a search and yee shall find the answers...

 

best mods for the money are a cai, exhaust, headers, and intake swap by far

 

Mitch I'm typing this out for you and the next 200 people who ask this question not because it irritates me but because I wish someone else would have done it for me (I know that takes the fun out of it), if someone doesn't agree then feel free to set me straight I'm not the local expert by any means. Maybe we can refine it and sticky it so we can just point up in the future.

As for your ideas....The stock ignition system is great, I wouldn't change any part of it unless you suspect there is a problem. Diablo doesn't support the 08' I don't believe so a handheld is out. If you want a decent tune on the cheap your best bet would be to go with a mail-order tune. There are few mail-order tune options I know of for the 08', Trifecta and Will @ Overkill. Overkill mail tuned mine and it woke the car up considerably, the website is www.getoverkilled.ca. Total cost after core fees and refunds was $199.

He can be hard to get ahold of so if you don't hear anything back uh....just keep reminding him until you get a response. Great guy, just not the most responsive.

Trifecta I haven't worked with so I don't know good their product is, I've heard good things about Vince and I've e-mailed them a few times and they seem like good people. Their website is http://trifectaperformance.com/ they have a different process than Overkill and a bit more expensive.

Here are some of the cheaper mods I know of:

Gutted stock airbox: A few people have done it, got good results, free if you have the tools.

Cold air intake: do-it-yourself (easy), cone filter $40ish, tubing $10-$15, grommet for breather tube, clamps, drill and a few other cheap items. Time to remove old airbox and install assemble new intake like 1.5 hours max. DIY heatshield would make it a bit more $, some people run fenderwell intakes to keep their IATs down, a bit more work going that route though.

Poly motor mounts: won't gain actual horsepower but it makes what HP you have more effective. Think they are like $80-100 bucks IIRC.

4T65E Transgo Shift Kit: Like $40-55 from different places, easy to install, DIY in the sticky section at the top, like an hour-ish of work. Decreases shift times, more firm, etc. No power increase obviously but decreasing shift times by a few tenths is as good as the same amount of horsepower it takes to produce the same effect in my opinion, and much cheaper.

Cat delete: Illegal , $20-30 bucks to have a straight pipe put in, or sell it and recoupe the cash, you will get slightly better flow, won't gain much, probably under a handful, car will be a few lbs lighter because those things are heavy as **** compared to the straight pipe that went in mine. Would need a tune to benefit completely, remove the CELs and change the cat overtemp strategy to avoid potential AFR issues.

Other mods aren't so cheap....

On the exhaust side it varies with your approach, cheapest for the most power is probably an electric exhaust cutout? Not sure about these but I think they are obtainable in the $150 range used.

Hogan downpipe would be next, I think DP5S or DP7S has the high flow cat IIRC. The non-cat DP is $120 off the shelf. Not sure of power gains stand-alone would work well with custom exhaust.

http://www.hoganperformance.com/WBodyGM.htm

Magnaflow makes an off-the-shelf cat-back system in the low $500's that is bolt on. A lot of people push this to the top of their list because it's a good bang for the buck and supports future mods. Part number is 16726, shop around.

Doug Thorley headers are out there here and there, if you are lucky you can find some in the $400 range used. These are probably one of the best mods overall for this car, IMO.

http://dougthorleyheaders.com/

LS1 intake swap can be done for relatively cheap if you know what you are doing and are frugal, DIY at the top for that. Intakes can be picked up pretty cheap, LS6 delivers more power but is more $$. Either would require a tune for full performance benefits.

Higher ratio rocker arms can be picked up used in the $300 dollar range, add 10-20 whp depending on the lift. Not hard to DIY if you have the right tools. You need better springs to support the extra lift, low mile LS6 springs are the cheapest option but not the best option. I got mine for $45 shipped.

Cam...not terribly expensive depending on what you go with, labor is what gets you. Gains are variable.

There are billion other more complicated far more expensive options that I'm not even going to comment on... head work blah blah not my neck of the woods.

Before you mod anything I would read the transmission problem count sticky at the top! Mine went at 60k miles bone stock, not beating on it, more power will likely expedite this.

Transmission mods... just see tripleedgeperformance.com

I always buy used, good quality ****.

Just my two cents.

 

Dam good post redlightrampage!

 

Invaluable information. I'm sure future newcomers who discover this thread will greatly appreciate it.

 

Good write up I'm still willing to bet within 2 weeks we will have another noob ask the same question again.

 

right think about that...i did a search and i ended up here....

 

you say intake swap... im trying to find out if the ls6 intake matches up with ls4
if it dose then might i need to change out the throttel body and a few of the sensors.... if i change out sensors dont i need to re program my ecu????

 

do NOT go MSD anything...

do NOT change the MAF sensor - stay with the stock one, with the screen in it!

for a programmer, you want the diablosport Trinity... which I can help you with...

 

Thanks Dave - just glad to have something to contribute.

Didn't know they had Diablo support for the 08'...

 

Don't forget that Vector Motosports does mail order tunes. I don't know if anyone on the site has tried em.

 

I would stay away from mail order tunes.

 

I agree with that for the most part. I think mail-order tunes are good if you are content with a stock or near stock setup and want to do it on the cheap. Once you start making changes I've realized it gets complicated quickly with finding someone to data log for you, sending/resending modules, just is NOT time effective and a pain in the *** quite frankly. If you are like me and **** it's very hard to get the tune 100% the way you want it via mail-order. I tune my own car now and I'm still making changes daily.

 

my bad... didn't notice he had an '08... right now, the Trinity does not support it....

but as soon as their E67 ecm support is done, there will be an update for it so that it will support it...

and I know they've started on the e67 support, since the owners both have new CTS-V's with the e67, heh...