Water Cars, Hydrogen Oxygen Booster, FACT of FICTION?

Over the last few months I have been researching HHO (or hydrogen hydrogen oxygen gas), came across many websites, with scientific proof that in theory it wont work, but also found many more videos, schematics, patents and proof that they do work.

Firstly you need to understand how it works.
This is what I’ve found.
You’d need to create a machine to convert water into Hydrogen Oxygen GAS, by means of electrolysis device of similar design to the magdrive (which apparently is a waist of money) or something like Stan Myers device.

This would be powered by your alternator some models I've found boast only needing 12volt and 10amps, also use an amp regulator, set to max 20 amps.

Connect it to the fuel intake (after the fuel pump) which creates a vacuum to suck the gas out (remembering of course to install a flashback arrestor).
Of course this is not enough to power the car completely, but apparently can improve gas mileage on average up-to 40%.
In one case I found someone had increased there mileage by 70%.

The thing scientist argue is, Faraday's laws of electrolysis, meaning the required electricity to split water, outweighs the output.
However, home and amateur inventors have found, up to 300% increased output. Just search for hydrogen fuel cell on youtube. I’m not a scientist or an inventor, and as such am my thinking is not bound by such laws.
For those of you who do not think this will ever work, then why are there so many for sale?

There are also companies that exist that use this electrolysis process, not for cars but for other purposes like Xogen Technologies for the treatment of wastewater.

Conclusion
I think this is entirely possible, I would combine this with solar power, electrolysis and also John Whites invention that can burn salt water using radio waves.