I'll keep you'all informed if you don't mind me rambling on. LOL The factory pistons were cast pop-up's. The Egge replacements are also cast pop-up's. They are 10.5:1 just like the factory ones. I ordered cast rings. Steve at the machine shop said the cast rings are more forgiving and seal better for engines that don't get driven much and sit over the winter. They deal with surface rust in the bores better than Moly rings do. Race engines that have moly rings seal better but usually get rebuilt every season. Makes sense to me. I'll keep you posted. Toolman