Thanks a million feral !!
My pc's on the blink and i've just read it now on my parents pc. I can't get enough of that tech stuff. Just as a point of interest, I am doing mech engineering at uni and I have passed thermodynamics - the stuff you said really makes sence but would have taken me for ever to think of myself.

So then, the fact that some people run 12+ and others only 10 (as noted by current posts on this thread) i guess is due to cams, squish, heat factors, and numerous smaller factors that tally a reasonable difference.

Do you have any figures for dynamic c/r that would be a good aiming point for 98 ron??

I would love to hear about the ceramic coating as well if you wouldn't mind !! haha!

Have you any experience with cam picking and desktop dyno or similar simulators ??

Daniel