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01-08-2004, 10:11 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, 10:54 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 www.clubgp.com 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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