The "computer " on one of them is only an air fuel monitoring gauge like the one below. I haven't run across any yet online that use a computer to do anything. Do you have a link to a page that shows one, I'd like to see what it does.
You can also connect a potentiometer to a motor contorller to control the amount of volts to increase or decrease hydrogen gas production, but that is a manual swich, not computer controlled.
Air/Fuel Ratio Monitoring
In able to get good miles per gallon gains, in a newer fuel injected engine, you will also need to monitor your Air/Fuel Ratios that your car's computer puts out. There are many ways to do this, the best and least expensive is the
"Smart Fuel Mixture Display", a dashboard mount box. Other ways is to install A
EFIE, or a
ScanGaugeII, it will over ride your "Check Engine Light". You will need to lean your fuel consumption, the addition of a good egas producing hydrogen/oxygen cellwill keep your engine temp.s cool!! We highly recommend watching your temp. gauge when first installed, to see it will work for your car

Photo of the DC pulsed motor Controller
DC pulsed motor Controller
A simple solder kit for
$22.00plus shipping. It can take 12 volts up to 25 amps, it has a 555 mosfet that pulses the signal much like AC does already. The pulsing action at the right frequency (about 8, on a pot. 1-10) helps in more egas production. The Hydro Booster will work without it, but to add more egas what the hay. You hook up a Pot, to the circuit and you dial it in till it bubbles the most. This is why clear filter housing is good for experimenting, because you can watch the bubble action and show friends. They won't last forever, much like SS 4" pipe would be best for long time applications