Awesome, that thing really hauls the mail! I watched a few of the related videos where he has the camera in-hand while riding a trail and it is really moving quick. Those big outrunners definitely power it well.
One thing I'd say is it needs some type of "brush bar" in the front to protect the motors. And maybe a custom, smaller, battle-hardened TX that would take spills better than the Spektrum one he has. Buy a cheap HK 2.4GHz system make something out of that.
Thats very cool. My boys will freak when I show this to them. How much did it cost you to do the tranformation? What are your electronics on that thing(ESC, Motors, RX, and whatnot? Nice job, nice toy, and nice videos. Thank you very much for sharing with us.