if you are lookin to use a gm tranny and claim that they cant make one strong enough to hold 500 hp, you should call the guys at ultimate ( charlie shafer and jason hunt) they have a sfwd cobalt that puts down way more that 500 hp and has seen i believe 9.30 at like 155 quater mile passes on a auto gm tranny...so maybe u should talk to them about your options with the cobalt trannies....just my opinion