A roots compared to a twin screw (they are totally different in design concept) is not a good choice. The roots is a lot less efficent at moving air than a twin screw. That means at the same boost, more heat, less power output, more power input to pump the air. A twin screw at a low boost with a good tune would be a better solution.

The Saleens do look cool, but to me that flat wide inlet runner looks restrictive to flow. The Saleen may be quieter, but if you are packing a blower why keep it quiet ... half the thrill is hearing that mother go to work.

 

The problem is the Ford tune is absolute crap and dangerous. You need to have any blower install custom tuned. Don't trust the canned tune. One guy can dyno his Ford tuned car and be fine, then you put yours up and you're running a dangerous A/F....

Always custom tune.

 

There is no problem with the flow on those - and lemme say this, the minute you swap out that stock 4 inch Saleen pulley and go smaller? Dude, the Series VI will sing, trust me (mine does - just need to get a clip with my new tune and set-up))

 

My whipple has been very streetable. In the rain however, its VERY easy to loose traction (4.10s and 3000 stall converter). Anything more than probably 1/4 throttle in the first few gears just slides the rear end around, and much more than a touch from a stop will spin the tires. (I have factory tires right now, so that might not be helping) It's like driving a powerful truck with nothing in the bed, an open differential and bald tires in the rain. Fortunately, I used to drive a truck just like that back in Louisiana, so I'm used to driving in the rain with not much traction.

In this respect, I'd say the low end of a twin-screw is probably not the ideal supercharger if you live in an area that gets alot of rain. A supercharger that has torque hitting harder in the upper RPM instead of one that has lots of low RPM torque would probably be better for a car that has to drive in the rain alot.