I have stage 1 flash so 91 or higher is recommended. Also, the 1330 has a 12:1 compression ratio which is pretty high and would run better on higher octane fuel to prevent knocking. Since I don’t know the exact parameters of the ECU and where the timing is set I prefer to run the highest I can find at a pump. The Optima just happens to be a 95 octane (because I have never seen a 87 race fuel) and its ethanol free which is always a plus.