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GTP boost?

01-08-2004, 09:11 PM
Just a simple question. I have a 98 GTP 103k miles only mod is using a 99 gtp intake sleeve and a 9" K&N cone. I Have read that a stock GTP is putting out 6-8 psi. I just put a boos gauge and im putting out 10psi at 5500 Rpm, now to me thats a lot of boost. I would like to put a smaller pulley but im afraid that to much will damage my car (its my every day driver) My question is how much can I safely go to?

Thanks in advance

01-08-2004, 09:54 PM
I think 15-17lbs of boost is the limit on the GP

I'd say open the exhaust up alittle. That will drop the boost a bit.

More important than worring about how much boost your getting is how much Knock Retard are you getting.

I see about 12lbs of boost w/ my setup. On 93 octane I see around 2-3 degs of KR. With Race Gas(104) I see 0 KR.

You can read more about KR and its importance in this article--

Go to and see if there is a local club that you could hook up with. Someone will have a scan tool and more then willing to scan the car and see what kinda KR you are seeing.

I think you'll be ok with droping down to a 3.4 pulley. If you plan on modding more I would suggest going with a Modular pulley system, that way you can change pulley sizes when ever you want.

Hope this helps alittle.

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