Its to small for the mods (that pulley size). Stock exhust manifolds, and the DP flex (only 2.1 ID) suck. Remeber its a non IC blower, “heaton”. And stock was a big ass 3.8 pulley 7psi. Anything over 10psi without some major intake charge cooling (IC), or better cly filling (cam,heads,headers). Spinning the blower faster, just heats the piss out of the intake charges more. It will knock, ande pull timming, not make any more power. Your feel a little “faster” with more tq under 4K, but it knocks up top. And you slowly kill the motor. Get headers or a cheap IC 1st Pacsetter just came out with what looks like a good/buget setup.