BTW, would it be prudent/benificial to re-time the motor if you changed your regular fuel usage significantly (from pump gas to av) gas ? Does this resistance to detonation help if the mix is leaned out?
I thought ethanol added resistance to detonation/octane, like E85 {15% 87 octane, 85% ethanol} has a 110?? octane rating. Why would an apparent change in motor performance be noticable then? Do you mean pure as in less inpurities?