Come to WCBF 07 (click the link in my signature) and you can fill up with all you want. But to be honest, your car probably won't benefit by more than 93 or 94 octane in mostly-stock form. Anything more is just a waste of money.
I have a local source for 100 octane UNLEADED race fuel. That'* what we run at Woodburn Dragstrip every summer.
Keep in mind that for your PCM to retard timing, it'* already detected knock or detonation. It has to happen for the PCM to try to protect the engine from further knock.
What I said about CA'* fuel blend is the truth. I have 92 octane everywhere up here. In CA, as soon as I cross the border and fill up, my car acts like a dog in comparison to OR fuel. Even if I bump my octane up a couple points. The blend is just plain rotten down there.
I generally have to bump my octane level up to about 94 or 95 in CA just to have the car perform as it did on OR 92 octane fuel. As a rule, I always top off the tank in OR just before crossing the border going south, and if I have to buy fuel in CA, I buy just enough to get me back north and across the border.