Here's an interesting reply from one of the f00s at the "other" board:
"First off let me explain the fundamentals of a supercharger. A supercharger is made of a a moving part which assists the the engine breathe. This moving part is connected to the belt which is driven of the engine. So if the engine is under full throttle it is building boost some what linear to the revs of the engine.
The roots supercharger is used as a positive displacement. It spins slower than any other blower but it pumps a lot more air per revs. The design was made to help help assist engines gain torque everywhere in the power band. This increase in torque will give you power in the entire powerband as well. Since it spins slower the lubricant is self contained and the unit is sealed and the lubricant isn't required for replacement.
The centrifugal supercharger is used like a turbo except its is driven of the belt rather than exhaust. The belt that drives from the engine sends the force to the inside the unit. Within the unit the gears increase the speed of the compresser wheel. The reason why its a centrifugal is because the wheel will initially pump air in form the inducer(inner side) and when it reaches the target RPM will pump on the exducer(outer side). So the flow from this supercharger isn't linear like a roots blower. This design was made to help propell muscle cars make more power at high revs since they can't breath very well. ( They use an extremely high tech Single Under Head Cam Design dated back to the 1720's)
The advantage of running the roots is that is can build boost right form idle. It will give you of the line better start. The advantage of the cantrifugal is that it will give you very high top end. Both of the two units behave totally different. The disadvantage with the JRSC is that it doesn't have a intercooler. People are using a water/alcohol injection to get the same results.
The Vortech unit since it spins at high RPM (like a turbo) needs an oil supply line and drain line.
The driver's seat the JRSC will feel a lot faster since it has low end torque. The Vortech has its torque at high RPM which makes its power at top end seem insane. The Votech actually starts to come alive at about 5000 RPM Which is just about when you hit Vtec. So it feels like a cam that breaks the laws of physics. The exhaust note resembles a Sportbike. Everyday driving with the vortech will make you shift down all the time, whereas the JRSC will make you give it just a little amount of gas. You won't even need to see over 6000 RPM unless you are at the track. The Vortech will seem like it takes longer to get where a JRSC is already there.
The JRSC will get you better gas milage when you are just piddling around. The Vortech will not help you at all here.
The one disadvantage with the Vortech is that the unit mounts to the tranny. So you might as well buy that ACT extreme clutch w/ SS disc and aluminum flywheel and Quaife differential before you install this unit. Your factory clutch WILL NOT hold at all. Or else you will be seing your self remove it all again.
For street use a JRSC is very practical. Its even more practical than the stock with basic upgrades. The turbo comes some where in between but it opens up a whole bunch more problems. The Votech gives you most top end than any of them. Although, you can size a turbo to give you the most top end.
The JRSC will run out of huff at about 350 HP but the Vortech V5 will make upto 580 HP!! But you can't make this on your engine unless you have the $$$$ to make it happen."