If you drive the majority of your time in the low and mid range RPM bands, then the twin screw supercharger will give you much more horsepower and torque than the centrifugal supercharger in the low and mid range RPMs. Almost all of my street driving is done in the low and mid RPM bands and even at Viper Days I only went to 6000 RPMs about half a dozen times (150 mph in 4th gear).
If you spend most of your driving time (by timing it on the clock) in the upper RPM range, then both the centrifugal and the twin screw superchargers with give you about the same power as long as they both are producing the same boost level. But the twin screw supercharger would get you there faster because it produces more power in the low & mid range RPM bands on its way to the high RPM band.
I chose the Roe Supercharger System because it is twin screw and compliments my driving style of street, pleasure, and some track perfectly. It also can scare the **** out of me at full throttle because of the tremendous power in the upper mid and high RPM bands.
I have a newer Viper with the hyper cast pistons and can only run 5 pounds boost safely, but older Vipers with the forged pistons can go up to 8 pounds boost. I think the price for Sean Roe's Supercharger System with the higher boost kit is very competitive with the new centrifugal supercharger kit coming out.
