Looking at the kit,this appears to be one of the many available under different guises that have been around since the invention of the motor vehicle, Basically you fill a canister with water and feed it into the inlet manifold,thus adding once it vaporises oxygen and hydrogen (H2O) or so the theory goes.More bang for your bucks???
Mind you some impressive glaims,but then Ive seen them all before.
Regards
Tony