I took the stock one, the wifes cat 800 rotax. It was good no problems. The fuel injection fuel economy is great. We had to back track 15 miles and the 840 teryx cars were running out of fuel and one was dead empty and had to be towed back in. I made it back with about a 1" of fuel on the bottom of the tank.(tree branch gauge) fuel gauge said low fuel when we were on the way back to camp the first time and I went back up and found Joel and still made it back. Im pretty happy with the fuel economy. 73 miles on Gps and I used 7 gallons and we were pedal to the metal almost every bit of the way. running almost 60mph in the wash not bad.