Just to throw in a few of my comments in the debate, coming from an STi with tuning and lots of time to mess around with engines.
1. Check out the "how things work" web site (
http://auto.howstuffworks.com/supercharger.htm and
http://auto.howstuffworks.com/turbo.htm) for info on turbos and superchargers, but the info is a bit dated. There are lots of books out there, too, for the truly interested. I've collected most of the more popular ones, so I can give you thumbs up or down before you buy. First lesson - a turbo is a type of supercharger. The complete term is a "Turbo-supercharger." However, I like lots of folks use the term "supercharger" (sc) to mean a non-exhaust driven forced induction system.
2. Keep in mind that there are two types of (non-turbo) superchargers, centrifugal and positive displacement-type (roots, screw, etc.) They are different in applications, and some of what was mentioned earlier only applies to one or the other.
3. The biggest differences in output between a turbo and a sc is efficiency. A mild to good turbo will return a 80% return on power increase (100% being double the power of a non-forced induction engine, all things being equal), while even the best supercharger rarely gets over 50%, though this generally applies to positive displacement-type which is the most common on commercial vehicles.
4. Also, the boost curve is very different because the rotation of the supercharger is directly in proportion to the speed of the engine. For instance, a "properly" tuned supercharger will get the most boost at the highest engine rpm, while a turbo can make peak boost long before redline. And yes, turbos lag, but proper tuning and design engineering can minimize the lag.
5. Finally, another difference is cost. Generally, a turbo system with a customized exhaust, tubing, intercooler, and LOTS of install time will far exceed the cost of a simple supercharger. The SVX is a little unique, but on other cars a complete single turbo will cost roughly twice what a supercharger will run when all is said and done...