Superchargers are belt driven, and that doesn't mix well with low torque engines. I've seen dyno graphs of tegs on JRSC, and they pale in comparison to a car with comparable preparation and a turbo. I'll try to find the links and post them later. You should also consider the fact that increasing boost (if you decide to take the risk) on a supercharger is a complicated affair (change belts, fiddle with all kinds of other mechanical crap).

With about the same start up cost (for a turbo kit, or your own kit) you can have a system with quite a bit more power potential, and is slightly easier to maintain IMHO.