compression difference
I don't know what premium fuel you guys have but all the stations here in WI have NO ethanol in the premium, it is 93 octane, this is from Kwiktrip, now alot of the guys around here that don't want to pay for race gas have switched over to E85, E85 has 110octane and theres a guy at our weekly car show that is running it in his TA 455, and he is running 13.5 to 1 he loves it you will burn approx 30% more but it is waay cheaper than race gas. just a thought if you want to run 13.5 to 1.