With alum heads and proper cam...some have gone as high as 12:1 believe it or not! Not saying you should do that. 10-10.5:1 is more than acceptable on 93 oct. Obviously not with a blower but n/a - nitrous. Remember that to maximize the power potential you will have to run a fairly aggressive cam. So drivability may slightly suffer. You don't have to get carried away with this to the point of vacuum issues for the brakes etc. Talk to your cam expert. Run the tfs heads(the new 11r design) in 190-205cc with a 56cc chamber and the proper flattops. It will run real well and you'll have heads capable of "growing" if you jump up to a bigger engine later. The 205 heads are capable of supporting 650hp right out of the box(n/a)-1000 with forced induction.