a gen 5 blower works better then a gen 3, so if you had a gen 5 you would only want to drop to a 3.6 with out further tuning, or a cam and a inter cooler, aka, some more mods. same goes for the gen 3, most just do a 3.4 with headers. but you can go smaller with a ic, cam, flow mods basically.

you got a few texas guys who tune on the board here, with any luck one will pop in here.