why are you worried about the compression??? if you are starting with a 8.5 to 1 motor and turning a blower at X percent to get 7 lbs of boost you can do the same thing with a 10 to 1 motor by turning the blower slower and keeping the temp down on the intake and achive the same amount of boost with a slower turning blower and still have the ability to go buy race fuel and really rip it up with a higher boost if wanted?? just my 2 cents