It's really up to the tuner, and what he wants out of the car. I could have sworn he said he just wanted 300 whp in the OP. 10:1 should be just fine for that without any detonation issues. ITR's and GSR's run higher compressions with that, and 16 psi is a cakewalk. The slightly higher compression will give him a much better throttle response out of boost, and make him more power at lower psi.