Hydrogen fuel kit

Does anyone have this system installed,car or lorry?
If so what’s the ups and downs of it,or is it a load of codswallop.
Have to say after some research Im nearly convinced .

I know some lads who used to fit them. From what i remember the theory is it mixes hydrogen into the air intake system to make it run more efficient? It never took off so i am assuming its a load of rubbish. Hydrogen was produced from tap water and a small electrical current.