someone stated that the slp 727 had the same size piston as the d8. I just took mine apart at 1700 miles and everything looks great (727) these are wiseco double ring pistons and the exhaust valves are even bigger than the stock 600 but slp reroutes the coolent, only thing i found was my mag side exhaust valve was full of water and the spring has lost all spring,possible to order these pistons to end season for some. Big Horns just got dumped on and away we go