This gets me to thinking, when we raced stock cars, we added an octane booster to our gasoline. Can't remember the name of the stuff, or how much it boosted the octane, but a quart was $8.00 or so and did ten gallons of gas.
(The rules said "pump gasoline only", but everyone had their own formulas).
Wonder if they still make it. Although all of my small engines run fine on E-10.