Hi i just bought a wr450 with a athena big bore kit installed. What octane gas should i be running in it? I have available near me 91 octane gas without ethanol and 94 with ethanol and av gas. I can get race gas but at around 8 dollars a litre its not really something i want to use. Will 91 be ok in it? Can i mix in some avgas or will avgas be as bad as ethanol?