My engine is the B16A which comes stock with 10.2:1. When I rebuilt my engine I choose to install 9.9:1 CR pistons because it would lower the compression just a bit to still have good response while not in boost, but still have good repsonse once I am in boost. I was pushing 12 psi, but soon I'll push 15-20 psi on a much more efficient turbo in the future while still sticking in 93 octane, but a conservative tune of course.