Remember when you could get 120 octane from Sunoco? My Road Runner used it...
You can get 110 locally at a dirt track, some marinas and certainly at small airstrips. My Subaru turbo has a Cobb Accessport tuning system with five settings, from no turbo boost all the way up to requiring racing gas, 110 octane. I did it once just for a hoot, and it was. Totally different beast, glad to have had AWD in it, lol.