Sorry mate but this discussion is pointless unless you know what your current compression ratio is. We cannot tell you squat, for all we know you might have a heavily shaved head or shallow dish pistons and already very high comp.
Read up this page and download the software, it's very handy, it will tell you static and dynamic comp. You will need a reasonable (although not expensive) set of calipers, you'll need to measure the bore, piston sizes and calculate the volume of both the head and the piston dish etc. The calculator will tell you what your compression is.
THEN, once you know your compression, you can start adjusting numbers to work out how much you need to shave your head to reach 11:1. Asking here for a simple "take 10 thou off" won't get you anywhere.