I think it is real, but doesn't have much effect. The front end doesn't come up b/c the jet isn't connected to the drivetrain, rather it is just bolted on so it only pushes the quad forward. The jet prolly only helps with acceleration and not really top speed, since the jet is connected to the throttle, the engine can only spin so fast.
In reality it is prolly mainly for looks and sound.
Tell you what? He sure grabs some attention. It isn't a jet persay. Actually a rocket combustion chamber. Theory: mix two gases and provide one outlet directed opposite to direction of travel. The N2O, and O2 tanks are great for size and weight. He could prolly try experimenting with other "historical" gas combinations and get great thrust results. Damn cool nevertheless.