heres some vids of a twin screw cobalt from cobaltss.net, i personally would go turbo for the money spent, its making 280hp and 263wtq on 20lbs but 400+ is capable with a turbo on a ecotec pushing 20lbs, its still bad ass though sounds pretty sick

http://www.youtube.com/watch?v=pCwX9T1p6Ew

http://www.youtube.com/watch?v=cQSPLKBZArU