Pel,
I expect that the 120 octane race fuel at the same settings will actually cost you some power and ET over the pump gas. To realize any benefit you'll have to boost the timing to account for the added octane/slower burn. Every point of octane slows the burn time just a bit, to prevent pre-ignition and detonation in higher performance engines. You get the most power and best efficiency running the lowest octane (fastest burn) fuel that you can burn without the "ping" of initial pre-ignition.