I'm starting to go back to my original decision of throwing a supercharger in my LS Teg for the simple fact that I live in California, which is very emissions strict, and for the fact that Greddy hasn't released it's CARB exempt turbo kit for the LS and I doubt they ever will.
Either type of forced induction is great, it just depends on what you ultimately want to do with your car. Superchargers aren't nearly as efficient as turbo chargers for the simple fact that it takes engine power to spin the supercharger and all that a turbo requires is otherwise useless spent exhaust gasses.
Here's a video clip in Quicktime with a GSR that is supercharged. You will note that a supercharger has more of an "exotic" whine to it than the chunkier sound of a turbo.
Turbos, as mentioned earlier usually have a blow off valve that sounds cool, but a centrifugal supercharger also has a blowoff valve that essentially sounds the same. If you want to hear what a turbo charged car sounds like, (I'm loath to make this referrence but it's the easiest way I can think of) watch The fast and the furious.
Update: I tried uploading the video but it must have been a bit too big, so anyone who wants to see it can just email me and I'll send the video clip over. It's not very big, or long, so it shouldn't take too long to upload/download.
