Pump gas compression
You also have to take into account intake design, Temp, elevation, fuel qaulity(and specific gravity or said fuel), VE, ect.
But if your going for ALL OUT power, aim for 10.5 static compression and 8.25 dynamic. KB has a great calculator to help you figure this out. Found here
http://www.kb-silvolite.com/calc.php?action=comp2