[onewhippedpuppy]

Aerkuld, you make some good points. For a non-turbocharged car that is not designed to see positive manifold pressure, it is doubtful that the engine management would adjust the fuel volume to provide for a proper AFR and more power. Though their gains of approximately 10 HP with only the leaf blower are not obscenely large, so I'd say it is still plausible, if not likely.

Their biggest gains were by shooting a spray of NOx into the leaf blower (intake), which is far more believable. Basic nitrous systems are no more than a fogger head that inserts into the intake pipe, and blows in NOx. What they did is the same concept, but with less precision and control of the fogging.