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2005 GTP Comp G Boost problems!

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05GTPcmpg

New member
Hello everyone new member here. I wanted to ask some of you a question about my car, since Iam at a loss and most of you know your stuff about these cars so I will get to the point. I have an 05 Gtp comp g with 40,000 miles on it. Mods are CAI(fender), 160 thermostat, 3.5pulley, custom exhaust, colder plugs, boost guage, ported heads, ported lower intake, ported exhaust manifolds, custom tune at Paxton Performance. I did all of these modifications myself and I am a mechanic on the side. My question is I just got the car together and drove it for the first time and it will fly but the boost guage is only reading around 8psi at wot. Also the stock digitial guage is going all the way up, almost like the boost isnt staying in the motor. Could this be due to the ported heads flowing the air out? Thanks for any input and by the way the car has 0 KR.
 


Wait ported heads?

If so, yes.

You've increased flow to the point where you can go with a smaller pulley.

Around 10 PSI is a good place to be.

Try a 3.4 or 3.3 pulley.

That is granted your AFR is in a good zone (~11.2-12) and you're running at least 16* timing advance at WOT.

Also moved this one for you.
 
Alright thanks for the quick response thats the reason I joined this forum. Yeah I ported the sh#* out of the heads, because the exhaust ports are extremely restrictive as well as the intake ports. Its crazy I dropped 3 pulley sizes and boost stayed the same...lmao. Yeah my AFR is tuned in the tables at around 11.2 wot. Do you think it gained any more horsepower.
 
Hows the car drive?

If it seems much quicker, you probably did.

I'd suggest something to take advantage of the ported heads (rockers or a cam).
 
It drives good man, sounds awesome and feels faster, but I know with more boost it would feel better. Yeah i thought about putting a cam in but I dont really want to take away from the drivablitity of the car. I know that sounds wack but there is a thin line as you know between street car and race car. Car is still really quite until you smash it then it opens up. I guess I will try the smaller pulley and see what happens.
 
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