The best total timing(max advance) will be determined by the fuel type and quality,fuel jetting, AFR tune up, altitude and spark plug heat range The higher the altitude them more timing you can use, the hottor the plug the easier it is to get the motor to detoanate, same thing on the air fuel ratio and gasoline quality What altitude are you driving the car at the most? What type(E10,E15, non ethanol) and octane gasoline are you using and what brand and heat range spark plug are you using?