Nanner1 good to hear you got it flying better/altitude never occured to me.. im in the midwest and its not a problem out here/my planes would probally seem sluggish out there. from what ive read guys in the higher altitude areas loose up to 1/3rd of power because of air density. i know with nitro and gassers it would be a problem because of needle settings on carbs. bummer about half back.. the hobbyshop should be well aware of altitude issue out there and especially knowing its gonna power a aerobatic plane that needs high power to weight. to me if i had a shop and someone bought that plane i would definately reccomend the the 920kv or better because of that issue the 740kv outrunner would be weak out here even. how did it balance out ? and what type of run times are you getting ? also what prop are you using with the 450 ? it should be like flying like a rocket with the 450 atleast out here it would with the 450.