I made up a Turbo head for it and it goes 18,200 rpm now. Pretty good but not as much of an improvement as the ASP/Magnum head I made. Maybe some shimming or combustion chamber shaping may help. I think the manufacturer tested a lot of things with these motors. A bigger carb doesn't seem to do much either like a lot of motors. It is missing the boost port like most schneurle motors, likely to make it more reliable. Pretty good light motors though.