Its actually powered by the turbine engine out of the Hughes/ McDonnell Douglas 500 series helicopters - its the bubble-shaped helicopter...if you remember the films 'Blackhawk down' & 'Apocolypse Now' its the little one.
My brother has actually seen the show where he talks about that bike of his. As he increases speed, the horsepower also increases- so as he's going faster he gains more power. It's insane-