LOL the comments so far....
Ok, I didn't bother to read too much (especially on their site), but it sounds to me like they're trying to sell an electrolysis device.
Indeed, Hydrogen Fuel Injection (HFI) is a very good way to improve your fuel economy, and increase power. They have been using these systems on 18-wheelers for many years. However as far as I know, they do not offer such systems for light cars and trucks. The ones used in trucks are way too big to fit in our cars.
Here's a link.
Injecting hydrogen is not as easy as these scammers claim... Everything in your engine has to be modified, including timing, AF ratio, etc... If you simply vent some hydrogen-oxygen mixture down the intake, problems are bound to occur.