93 octane fuel, and 18psi on a GT2876r not a T3, and I have a 1.0mm head gasket and -22cc wiseco pistons, so I figure compression ratio is 8.7:1 or lower. I've been running 17psi on the street and haven't heard any knock yet, mid-range RPM though it's lower like 14psi though. Thanks for the advice, ...