Interesting - do you have a tune to take advantage of the additional octane (e.g. Advancing the timing)? Or do you see a difference even stock? If so, what blend are you running?
If you do half a tank of E85 and half a tank of E10 (regular gasoline) that means you'd be running around E48 or so? Almost 50% ethanol? I've never thought of doing that to increase the octane - intriguing.