Juan, there are and have been in the past ten years more kinds of HHO systems, designs, and ideas than can be counted. There have been Gadgetmen in this forum before who have detailed such systems. Ron Hatton was doing HHO before he invented the Groove.
You can put an HHO system in your ride if you want to. One Gadgetman who isn't active here anymore, is Dan Merrick. Dan is a fuel chemist and Inventor in his own right. One of the most interesting things in the HHO world is called Merrick's Gas, Dan came up with it. Will take research to figure it out, but if memory serves- it involved using ammonia in the electrolyte solution, possibly some titanium in the plates, and the resulting gas product was called HHHN.
On known issue, far as I've read with HHO is- the Oxygen in the HHO gas can increase the Oxygen in the exhaust gas stream. This can cause the upstream O2 sensors, to send a lower voltage output. That signals the ECU to increase fuel delivery. That's why EFIE's were invented by George Wiseman, to modify the O2 sensor output voltage.
The story goes, as I recall, that the ammonia electrolyte Dan used, resulted in extra Hydrogen in the output gas, and some Nitrogen too. There was something about the Oxygen in the gas being bound to some of the nitrogen, causing the Oxygen to be missed by the O2 sensors.
Aaron Murakami has a download info package available called Water Fuel Secrets, at emediapress dot com. He goes into detail about the role of nitrogen in Stan Meyers' Water Fuel and HHO stuff. I take anything from Aaron as serious stuff!
I never ventured into this, and I don't know if there is a commercially made system around that used these ideas. HHO has worked for lots of folks--but you need to really read up on it first. There are several issues to tackle with HHO systems.
It turns into quite a research and tinkering project. Gains can be had, IF you pursue it long enough.
This is why I got real excited and am still excited about the Groove. The Groove is simple, effective, proven-- and it's AVAILABLE To Do!!
Once one learns to do a proper Groove-- Like you have, Juan-- a door opens. No tanks to refill, no meters or knobs to watch and play with. Little or no extra parts to install.
I suggest, go ahead and play with HHO stuff if you like to tinker, hey that's OK!
But I bet you would get great gains, if you implement everything in the Instructions in your Kit, including the RVS treatments, in the fuel Savers tab on the front page here. You can upgrade your Ignition parts to the best you can afford. Spark plug Gaps! Tire pressures, and anything you can think of that is causing parasitic losses. Be SURE that there are no maintenence issues needing fixed.
For Mileage, it then comes down to how you drive it!
Ask Greg Kusiak, Heysoundude here, about what I'm saying. he Knows.
Tracy G