If the ionization level, both positive and negative, is excellent then even 1% of it will help enhance combustion chamber efficiency to give cleaner engine, cleaner exhaust and better mileage in the long term trials. Good Luck.
Surely you will get better engine power and torque characteristics.
Along with that, the combustion of H and O will also help boost the gasoline oxidation.
But, if you do nothing about the gasoline quantity for each of the combustion cycle during the HHO addition, you will be burning more fuel than you should.
In combustion point of view, it is good, but if you calculate the energy balance, you are actually using more energy than you should.
In an unpublished research done by one of my M.Sc. students on the use of HHO gas in a gasoline engine we reached very interesting results : Fuel consumption is reduced thus improvement in engine performance is obtained. Furthermore no CO emission was noted and HC emissions are reduced. Also an increase in CO2 is noticed. What do you think of this?
HHO is best for improving the performance of the engine. NOx will increases and HC emissions are reduced. we alredy conduct the experiment based on this paper " Improving Performance and Reducing Pollution Emissions of a Carburetor Gasoline Engine by Adding HHO Gas into the Intake Manifold " SAE International