I think you should put HHO on hold until you isolate your smoke source.
Basic rules for exhaust smoke is
Blue smoke = oil, (rings or valve guides...)
White smoke = water (head gasket, cracked head...)
You can check your water consumption in your radiator if you have white smoke. If it looks to be lowering fast, then you can assume that is the problem. May also check your oil color, to make sure no water is going in there (it should be black not brown)
Other rules when it comes to exhaust smoke are more complicated and how HHO effects it can be involved. I don't fully understand them.
Example; water is a normal byproduct of engine combustion, they say 1 Gallon of gasoline (mixed with air during combustion) produces 15 Gallons of by-product water out the exhaust. Now If you add water vapor to the intake the by-product water in the exhaust goes down (to as low as 5 gallons of water).
When you're one step ahead of the crowd you're a genius.
When you're two steps ahead, you're a crackpot."