This is a cheapskate RB30 (stock bottom end, upgraded rings, bearings and rod bolts) supposedly good for 300 -350 awkw (although I would reccommend forged and balanced if you have the cash) so stock pistons, later model RB25DE head which has bigger valves than turbo and VCT which I am retaining. I think the CR will be about 9:1 but I haven't measured it.