After attending a few of the Viper Tech sessions around here, I learned that the best performance you can get out of your engine is to use the lowest possible octane rating that does not make your engine ping under load. So if your engine does not ping using 89 octane, you are getting more performance than if you had 93 octane in your tank. It cracks me up to go to this one 76 gas station around here, that has a 100 octane pump, with a price of $6.10 per gallon, and see all kinds of guys filling up their Mustangs, or Harleys. They think more is better. I explain to them that they are actually de-tuning their cars by buying the expensive gas. I usually have to add about 3 gallons to every tank full, to get my octane up to 93 so I don't get any pinging under load. Our premium octane out here is only 91 octane, and with my mods, it does not cut it. So don't be so afraid to experiment with lower octane gas.