there is a guy on the E46 board who supercharged his E46 M3. Yep that's a 11.5:1 high revving engine with a s/c. He claims that with 3 psi he saw near 350hp at the rear wheel.

He also said just about everything on the internals of the engine has been upgrade, forged pistons, etc, he also has a standalone engine management and upgraded fuel pump, injectors, etc.

He was supposed to go up to 8-9psi sometime this month... I have my doubts and I suspect his engine will go kabooom soon.