Its not only about to increase boost. You are limited by fuel, octane, knock, compressor housing size and much more. 22.5 PSI on 100oct fuel at 10° timing advance is the limit what my tuner (not Jarek) consider as a safe limit for this setup. We are about to tune the car for WMI right now. And no, it does not have to do anything with OTS maps... i am on custom tune. Engine is stock. 11:1