if ur runnin 110 in a ministock theres no way its legal then, the compression you would need for that to burn right and usable is overkill for a stock motor,,, what kinda car and exactley what has been done so we can help a little more
Delta Sonic on Ridge Road in Rochester has 104 octane fuel. Usually I stick with 93 in my mini, I can't say that there was ever a noticeable difference in running anything higher., except the smell of the exhaust. If you go to the rez, you can get 93 octane without ethanol.
have you ever tried changing the jets? if you're running a holley 500 the carb is to big for the motor so lower jet size 2 sizes at a time until you get a good plug reading but remember new plugs each time or you could also try a hotter plug