I have a 03 yz 450, I'm thinking of putting a 478 big bore on it. All the kits I have found have a 12.5:1 piston in them. I would like a 13.5:1 piston. I can get a aftermarket 98mm piston in 13.5:1 but not in a kit. I can't decide what to do, stock bore high compression, big bore stock compression or a big bore and order a high compression piston from someone else. Anyone have any dyno numbers of stock bore w/ high compression piston vs. big bore w/ stock compression or high compression? I don't mind running race fuel so that's not much of a factor, I'm just curious what the best power for the money will be?