So what exactly is a supplemental hydrogen generator?

Hydrogen engine performance boosting systems are known as Supplemental Hydrogen generators. A supplemental hydrogen generator is basically a tank that holds distilled water and an electrolyte, such as potassium hydroxide.The water is charged to induce electrolysis, which separates the hydrogen and oxygen molecules. The hydrogen & oxygen that has been released is then collected and forced into the engine through the air intake system. The added oxygen increases the octane level of the fuel.
Once the supplemental hydrogen is in the engine, it helps increase the flame spread during the combustion process. In other words, the hydrogen makes the flame in your engine burn faster.