Do you mean the swing valve? The stock exhaust exits in the opposite direction than is desired for the engine mounting configuration, so the swing valve cast unit was cut and then material was added and welded to allow the exit to point more towards the rear of the engine.Could you please elaborate on the source for your turbo exhaust housing? Are more available?
Here is a picture of the modified 2.25" next to a stock 2.5". You can see the modifications on the mounted swing valve
Hope that answers your question.