We have a Sunoco here right next to the track that sells 110 Octane Race Fuel....I won't run it but have put in 5 gallons of 100 Octane with 5 gallons of 93....lets say its 97 pumping through the pistons. Not too bad....I definitely noticed a difference but only tried it once for the track....don't want to have any future engine issues...you never know.