It would be snake oil if you were going to be using the Hydrogen produced as a fuel replacement... as a combustion catalyst, however, the equation is markedly different.
Reducing the activation energy of the thermodynamic event can get you to a cleaner, more complete burn, and that can net some measurable gains in efficiency, with relatively little input, energy-wise.
I prefer to suspend judgment until somebody tries it out and gathers some quantifiable data with a 6.5TD...
After all, propane is a relatively low-heat gas and shouldn't yield big efficiencies used as a fumigation agent, either, but it does, in a direct-injection environment. The amount of stress the system will put on the alternator is relatively little, all things considered - in this day and age of high-power stereos and subs - and so I think it's worth a try.
There's a company in Ontario, called Hy-Drive Technologies, that has been marketing a larger unit for trucks and busses for 3 years, with some fairly credible data. If GM had all the damn answers, we wouldn't have PMD issues, TD and Slim wouldn't be building a better turbo, and a spring on your wastegate wouldn't be necessary.
Please report back what you find out, Clark!
