Question, have you tuned your car yet? The gains will be much more substantial and much cheaper. In fact I would follow the tune, intake, header path to completion first before thinking internals. And internal look for bigger jumps like the big sleeve kit and then because top is off, maybe polish.. but to just open to only polish for maybe 5 hp gain,why. As to cams.. replace with what... again just play with the tune and adjust the VVT.Any benefit to having a NA's heads ported and polished?