I just had a look into that stuff. Basically it's meant for diesel engines above anything else, as it encourages a lean burn to potentially save fuel and in theory it'll turn from hydrogen into water as a byproduct of the combustion process to lower engine temps/EGT.
In theory.
Given the potential benefit vs potential risk, so a bit of fuel saved vs melting pistons by running unexpectedly lean, as well as the complete lack of any independant research into it on diesel engines (which is what it's designed for!) rather than petrol engines, I'd be filing this firmly under snake oil and removing it from the car pronto. Incidentally the few pages I've read about hydrogen injection refer to it being only of benefit at high rpm, which would indicate a relative lack of involvement in helping mid-range torque and certainly it's not going to be doing a damn thing unless you specifically map for it.