That's right ade, but you loose some with the heigh, gain some because of the bowls, my point wasn't so much where the CR is more so measure it so when the mapping day comes your tuner will have much more confidence

Coley give me the full spec, what pistons they are how much they have had off the top exactly. How much they stop down the bore and combustion chamber cc I can work it out for you quite accurately.

If you can't cc the chamber size then measure the head thickness

It's well worth buying a Burette for checking cc of pistons and chambers