I've written on this subject before as you might or might not remember. When I was having some issues with my rebuilt Pontiac I was looking for ways to make it better and more powerful since I do a lot of traveling within mountainous areas, and I ran across this site Superchargerpros.com.
It looks as if since my last visit they have given their site an overhaul and the design looks sharp! They offer great prices on their products and also excellent customer service to help you find just what you are looking for to soup up your vehicle.
Anything from a Buick supercharger to a Mercedes supercharger (and Pontiac too, which I'll be looking at) .. they have what you need!
Check them out if you are in the market.