Best 4 cyl. centrifugal supercharger?

I need your precious opinion in my quest to find the best SC out there for my application... let me know what you think

-- Facts:

My engine is a 2.3l Quad4 W41, all forged internals, bored up to 2.4l, cams, headporting, E-Honed intake man., full exhaust, Electromotive Tec3 EMU, cowl hood to exit heat, etc... A front mount intercooler is mounted on this car with 2.5 inch pipes all the way. Car is a 1992 Beretta GTZ.

The engine is presently running great with the Paxton SN-92 on it and it does not seems to drag too much from the engine but I know I could have a more efficient blower for this application. I bought my SN92 at first cause I got a great deal on it($600 brand new) and done all my testing and fitments with it, added a cooler to it and FMIC. Now I got 6psi from it after the air flowed thru the FMIC but I would like to get to about 15 psi. I could go with a Paxton VR4 upgrade to get +/- 13 PSI but I realized that the SN-92 is a big unit compared to my needs but I would really want to stay with the centrifugal supercharger setup.

-- Question:

Now I just need to determine if I'm changing to a unit that is smaller and better suited for my application or if I'm staying with the SN-92 and upgrade it to a VR4.

What's the best blowers for modded 4cyl. or 6cyl. engines?

Is there any source to find how much drag each supercharger model needs to be turned at given boost levels?

Let me know what you guys think Thanks for any inputs!

Eaton like the Racing Jackson unit which is the Thunderbird-Cougar style(M90). I myself would use a Turbo from a Eclipse and with that cross-head design it would be perfect. Do a Google search and many have done the Turbo install on the Quad4.