HHO gas, also known as oxyhydrogen can greatly increase the fuel efficiency of cars in which it is used. HHO gas is created through a simple process of electrolysis - the car does not run just on HHO but rather a hybrid of gasoline and HHO which powers the car. HHO has been shown to increase fuel efficiency by as much as 93% in some cases.
There are many HHO kits available online and installation does not require any specialized knowledge.
The ECU is the key to getting the most out of your HHO installation. EFIE's and O2 sensor modifications are inelegant and insufficient when it comes to getting your ECU to work with HHO.
The FS2-HHO Ed. has been specifically designed to solve the problem with late model ECU's by patching fuel mixture values on the fly. The FS2 is the best solution to a complex problem.