How about a small supercharger? I used to have one that i planned on putting in an old samurai, but never did. It was the size of an alternator, and would easily fit where the AC pump is on a sidekick. It used a 4-5 groove serpentine belt, and tensioner setup just like an alternator. Man i wish i had have done it. I sold it instead. Apparently it was off a subaru from Japan.