ORIGINAL: Birdieman4

Are your injectors stock? They may be your weakest link. I think your fuel pump could handle 5-6 psi, but if you have stock injectors you're limited.
centrifugal blowers don't "simply make more power" throughout the entire rpm range, only on top. There is now way in 2 identical cars, 1 with a kb, the other with any centrifugal blower, tha tthe centrifugal car will wil, let alone hands down. As a matter of fact, with capable drivers, the screw will win EVERY TIME. I know what your gonna say... In NMRA competition, these cars are all out race cars. That means they are purpose built cars with racing mods. These cars run very short racing gears, which works well with a tt or centrifugal setup. These cars rev A LOT higher with radical cams, which dictates the power adder choice. Since these cars ARE NOT street cars, they can't really benefit from a screw setup. -But streetcars can.
...Compared to a roots blower, maybe. Compared to a screw, I doubt it. As a matter of fact, in the dec issue of MM&FF, they do dyno comparisons between tt's, roots, screw and centrifugal. If you compare the screw with the Vortec, the vortec hp curve(11 psi) finally meets the kb in hp at around 5750 rpms. It takes that long for the centrifugal to match a screw in hp at the same boost. Roots is a different story, but I'm not talking about roots blowers. I won't even talk about the mis-match in tourque curves.

...It makes all the tourque across the board, not just down low.
That's all about driver. To make a centrifugal shine, you need short gears, the shorter the better to a point. Running really short gears also works against you for traction. It goes both ways. The bottom line is racing vs. real world. The screw is better for real world applications. I'm tellin ya from a guy who owned both, raced both, and streeted both. My screw car stock made less hp than my centrifugal car on the dyno and had shorter gears, but it was faster. Why? I was in a peak hp range longer. Why do you have trouble swallowing that fact? Look at the MM&FF december issue, which backs my argument.