Finish on piston has a lot to do with how they run also. We were shocked on our hi reving 2 strokes engines what a difference finer or coarser finish would do on power. We would make one in the cnc lathe and dyno an engine. Depending what the power was like we would change it and try again. We tried different finish on the turning getting better and also getting worse on our results. Once we found what we like we ran all of our pistons this way. That is one advantage of having everything in house.