A 2.5" downpipe will work OK, that is what my stock downpipe Syclone has, but I would like to have a 3" downpipe.
On a turbocharged engine , you do not want any exhaust restrictions, no matter what some people say about needing exhaust backpressure, don't listen to them.
I would go with a 3" mandrel bent exhaust , all the way.
