hey dude sweet jet, i like very much! ya think it's under powered? in my oppinion it aint, it's under propped and cavitating real bad with that prop pitch! try repitching ya prop to 14/19 or 15/20, it'll rip ya arms off, trust me!!! i'm running a 753 all freestyle ported with stock'ish carbs and a 15/20 repitched concord and it works very well, massive difference when i changed from a 13/17 concord!!