I have run a k9C cylinder with a BB insert in the head, the squish was tight .73mm I ran 2 base gaskets to get it to .82. The combustion chamber was 10.7cc. Great snap out of corners, good for shorter tracks but runs out of topend on longer straights. I do have to run a 50/50 C14 to pump gas mix, but I did run 20 litres of VP’s MRX02 to see how it goes, wow, big power gains! My only fear in running a tighter squish is the rod streching during over rev and smacking the head. I put on just over 10 hours before doing the topend and have 16 hours on the bottom end, which is in need of doing now and have had no problems.