You guys keep saying that, I don't understand it. I run 93, E85, 87, E47, it just doesn't matter, smooth as silk, the only difference is the power available.
I know there is a tune available that's designed strictly for 93 (and one for 91) but surely most tunes, where you don't specify, retain the stock tune's ability to run any octane fuel?
(edit to add) 2013 I have the E85 conversion and added an alcohol sensor which is what lets me do random amounts of ethanol. I also added an aftermarket clutch, burned it out, and added an even stronger clutch, which lets me use the full "red pill" power of E85, if you don't do the clutch you will have to take the lesser "blue pill" which is still pretty hot, and if you don't do the sensor you will have to reflash and do a near total empty tank fillup in order to change from one fuel to the other.