I've seen that somewhere before and thought it was pretty good, I like it. It's expensive though. The clear tubing is outrageous! The best part is he doesn't use a pwm. He has it attached straight to the battery. That "one way" valve however is not effective for a flashback !!! And the pipe tape is not near as good as thread compound by permatex(automotive stores). But that would be a good starting point for you to explore the advances that can be made. He also gets the amount of HHO due to the large amount of potassium hydroxide that is used and apparently 24 volts instead of 12, as he says. I use 12 volts, no electrolytes and start with 50 amps for the first min or so then drop down to 2-4 amps and keep the same production as if at 50 amps.
I ran a 2.2 liter Chevy Cavalier on less than that at idle and low load driving. It takes work and experimenting with what you may or may not know about cars.
Its done right or its not done !
Hail HHO.