Thanks for your reply! I've got some wossner pistons on offer. I can get the measurements from my friend. The reason I'm desperate to know is they are oversize and I'd have to rebore the block. If they won't work I will prob just go n/a for the mo and just slap some new rings in there. I can calculate the static comp ratio with these new rods, pistons, a focus rs headgasket and the combustion chamber but do I need to worry about the dynamic ratio at all?