Understand something about those octane ratings. Higher octane gas just raises the threshold at which your gasoline will tolerate heat before detonating. If you use lower octane gasoline in a high compression engine (especially on a hot day), you will hear some pinging from your engine meaning that the gas is detonating from the heat rather than a spark. BUT, your ECU compensates for lower octane by retarding your ignition timing which means that you will get a small decrease in power output. You can run forever safely on 87 octane gas in the ITR but you'll never get the same performance as consistently using 93 octane.