Weird. The factory CR for my L200's G63B was 9.5:1 (or was meant to be) I ran into grief getting the correct OS pistons for it and had to settle for a set that was slightly dished (it'll be down to 9.3:1 so not much of a drop). My guess on the CR for the twin carbs was based on it being a performance thing. Can't wait to see what it's like after you've got it up and running!