The pistons are forget Icon, .030" over. The piston rings are file fit, with a .004" factor; meaning an installed gap of .004 for every inch of bore. In my case, 4.030" x .004" = .016" minimum gap. Better to be a little on the bigger gap size than too small so I gapped all 16 rings to a strong .016" / tight .018" (don't have a .017" feeler gauge).