I tore my top end down because I was getting piston slap, but I noticed the tiniest bit of rubbing on both the powervalve and piston. Not really anything on the skirt but up around the rings the piston has grooves all the around, its hard to explain theyre factory not from dirt and stuff, and theyre worn a little flat. There's also a rubbing mark on the powervalve. Does anyone have pictures of their powervalves rubbing their pistons? I'll get some pictures up tomorrow if I can.