Pontiac Grand Prix Forums : Grandprix

How much boost will i get with a 3.4 inch pulley?

I have a 3.5 and Im getting 10 psi with no kr.

if you have a correctly modded car you should be getting around 10-11 psi.

but, if youre more extensively modded you may make less. you will make more if you dont have any flow mods. boost level is all relative to how much your engine flows.

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98 XGT - sold
06 impreza 2.5i 5 speed - stock, slow, and awesome

Usually you can add one PSI for every 0.1 pulley size you drop. But like Nick said it all depends on what exhaust size you have ect. Stock PSI is about 7-8 PSI

if i could run a 3.0 pulley and have about 8 pounds of boost i would LOVE IT.

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98 XGT - sold
06 impreza 2.5i 5 speed - stock, slow, and awesome

I ran a 3.2" with about 10-11psi...but there is a kid around here with a 3.4" and it cracked 15-16psi everytime he went WOT...and he has supporting mods too...insane

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2003 Blue-Black Metallic GTP Sedan - Almost Done...
2007 Gold Mist Chevrolet Cobalt LT - Custom CAI, NGK V-Power's, Muffler Delete, Custom Tuned PCM...Sure does have every bit of 130 FWHP
http://www.cardomain.com/id/03blueGTP