Hi there, allow me to recommend some alternatives that will actually net you a gain in your fuel economy.
A tune is a very popular way to unlock extra power or fuel economy from your engine. There are several companies that offer mail order tunes. Stick to SCT vendors. There are even some who are registered with this forum as vendors.
An electric fan is another popular modification that frees up a little bit of engine power mostly when you are accelerating or cruising at highway speeds. The stock fan does contribute to a little parasitic drag on the engine, and while cruising down the highway, you almost never need it. The gains in fuel economy and power from this modification are not huge, but verified ad nauseum, and are a favorite of auto manufacturers and the racing world alike.
Exhaust modifications such as headers or catbacks are also popular, though you won't find much gain from them.
A good set of highway or touring tires is a GREAT way to get a little better fuel economy. Make sure they are always inflated properly.
Regularly changing your fluids and using the proper viscosity of fluids helps too. Many people change to synthetic oils as well due to their long-life characteristics, and ability to continue to perform as normal even under extreme stress or harsh conditions.
The single biggest gain anyone will ever get to their fuel economy is generally in examining their driving habits. Do you find yourself accelerating from one stop light only to press on your brakes shortly before reaching another?
Before you consider adding an HHO generator to your engine, please do search on the internet for more information about them. Try to avoid sites that are selling HHO equipment, since they will throw plenty of psuedoscience at you to try and convince you it works. Most of the theory behind an HHO generator violates the laws of thermodynamics. When you hear people talking about wet cell and dry cell... Well, I'm not sure what they are thinking. The only difference between the two is the amount of the electrode plates that are exposed to the water. For some people, dry cells APPEAR to function more efficiently, because the part of the electrode outside of the water functions as a heat sink, and your HHO generator is basically the equivalent of a smaller "wet cell", therefore it will naturally use less current and produce an equally smaller output of hydrogen.
Now, I'm sure that there will be people who will jump into this thread soon enough throwing fits over what I have said, or talking about their "planned" cells or the cells they used to have, and sharing with you all their first hand knowledge about how their HHO cell converted water into pure unicorn farts to power the space shuttle, but I implore you, before you throw money away on this, please consider putting it elsewhere into any of the other modifications I suggested. If you still are not convinced, I would be happy to give you plenty of articles to read written by various automotive rags, engineers, scientists, NASA's Jet Propulsion Laboratory... But, if you still prefer to throw money away, there are plenty of guys on the internet who are sure their next version will definitely work, have a magical story about their last one that inexplicably disappeared, or just have ridiculous and unsubstantiated claims about their present system.
