Not that its gonna be very helpful because I've only ridden the thing 3 times, but I've just been running my dirtbike fuel. Which is more or less a 50/50 mix of premium pump gas and Sunoco race gas, mixed 40:1 with Polaris Gold. It seems to run killer. On my dirtbike, if I run straight race gas it seems to run hotter and I have to play with jetting. If I just run premium pump, it runs fine but I do get a bit more out of it with some race fuel mixed in. I've run Sunoco and VP with similar results. I would assume that this would hold true with the ski as well. Also things to consider are whether or not your state oxygenates or puts weird additives or ethanol in fuel like they do here in California. I live right next to the Oregon border so I try and buy fuel in Oregon because they don't put as much crap in the fuel (and its cheaper).