I just checked into the 4" dual wall rolled stainless tips that some users on here are getting. First off the place I checked at was a rip off, about 350 bucks installed, when I have seen people one here get them for around 150.

My question is they are not 2.5" inlets (the gt is 2.5" right), they are 2.25", so since it has to be adapted somehow in the weld when put on does this affect performance at all?
Thanks