I'll throw this out there, not sure if it means much. Read about a test some engine builder did on a small block Chevy, on the dyno, with the results of dinging headers, if it lost power. They went so far as to almost flatten them completely and saw no power loss, maybe 4 or 5 hp tops, they where dumbfounded? You might see a change in a poorly designed set over a top of the line set, but not the gains you're looking for, IMO