Grim check out Gollums post in the High Revving V8 thread. He talks about the Honda VFR800 which seems like could be a killer little V4. A little google research and most people show you can get close to 200 hp with a supercharger. Probably more with internals, cams, turbo's, etc. But the weight savings could be killer, not to mention mounting the engine way close to the firewall. I think it would be an awesome project if you could prep it and make it super light, CF/FG, no interior, etc. It'd be quick, peppy, sound good, and handle like none other!