Hi Guys, I'm new to this site and was recommend to visit, if I needed help. My car is a 2000 GTP with TOG header,THrasher CAI, 3.4 supercharger pulley and changed my exhaust and a set of Magnaflow mufflers. I have notice that since a changed my exhaust and put in the header my boost level has drop. Can anyone recommend what type of pulley can I install to get my boost up with causing any KR. Please Help

It's pretty much impossible to specifically say "this pulley will give no KR", but i would say from the header and CAI, you should be able to run a 3.25. Just to be on the safe side, you SHOULD autotap after this swap to make sure. If you do have an unexceptable amount of KR, you can save the 3.25 for when you get a cam or rockers.

And remember, just because the boost went down doesn't mean you're getting less performance. The boost should go down significantly since you have less backpressure.

Also, you didn't mention anything about removing the U-bend behind the cat. Was this done in your exhaust upgrade? If not, it's a simple and cheap way to lower pressure and reduce KR.

ferb!

Ferb is right of course - the boost pressure itself is actually irrelavent - what matters is the volume of air you push into the cylinders. Often when a smaller pulley is used the boost goes up but the performance doesn't. Why? Boost stacking, a situation where the engine cannot take the volume of air the blower supplies - the resulting restriction causes an increase in pressure in the intake manifold but no more flow into the engine.....a waste of power because turning the blower doesn't do anything but waste energy.

Removing any restriction in the engine - intake or exhaust side - will cause an increase in flow volume through the engine. If the blower cannot keep up with the demand, then the intake pressure drops. Now a smaller pulley can increase both pressure and volume going into the engine.