[Shane@DBPerformance]

400awhp on race or pump gas? It sounds like you are looking for something that will have some throttle response, so something like a 50-trim or GT30R would work. But it would be hard to make 400awhp without something in the 61mm size range on pump gas. The ball-bearing versions of the 50-trim aren't too expensive. The Mitsu exhaust housing versions will spool faster, but give up some HP. The Mitsu housings work fairly good on the 50-trim, they get a bit too small and restrictive when you start getting into 61mm turbos.