93 and tune for 93, make sure you get from a gas station you trust if you require 93 for bad things not to happen to your motor. If you go to the track then you can also have a tune for that loaded on a handheld and fire it up after you load up the tank with a few gallons of that.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.