My 511 has 11.3:1 static. I use Kroger 93 octane fuel. No sign of any detonation on the plugs yet. Just this year a have been mixing in a gallon or 2 of 110 race fuel to a tank of 15gal just for the smell. 3 or more gallons and it will run richer and I see it on the wide band. Exhaust note changes from crisp to a dull note and the car feels slower and less responsive.