Yeah I guess that's an option. What would be the difference in HP between a 100 octane race tune and 70/85 ethanol tune?? My tuner said it was only about 10HP from 93 to 100 so I am even wondering why I run the 100.You could have your tune are for a lower ethanol content, say E70. Will still get most of the benefit of E85 and not have to worry.