Will be pulling engine soon for sport600 install, I have an air grinder and various stone wheels to clean up and port out the openings of the manifolds. I was going to have them extrude-honed as well but I'm having a hard time justifying $500 extra. Does anyone have any before and after, seat of the pants or dyno feedback on them? Am I only going to drop a couple hundred RPMs of spool up? Would I be better off waiting for the Dupree headers for god knows how much?