I just finished the file fit and I went with .020 on the top and .016 on the second. It went well but it doesn't take much of turning the 'wheel' to get the rings filed down. It took me longer to 'deburr' the ends than it did to do the actual filing. I hadn't thought about the reduced scuffing of the piston but that's a plus. I originally went with the silicon added pistons for less expansion and a tighter fit to reduce cold piston rattle on start-up.