I will tell you a secret. I took my aquatune back & they got pissed & went to charge me 20% restocking fees. I filed a dispute with my credit card company over their 'money back guarantee' and won my 20% back.
Also pay CLOSE attention to your spark plugs or O2 sensor..which ever is easier...
Aquatune's style of advertising and claims doesn't inspire confidence. The basic idea is sound. You get "free" mechanical energy when the waste heat of the engine turns injected water to steam. Cools the engine a bit too. But it's not so easily done, and I'm thinking Aquatune doesn't succeed at getting the idea to work. In their marketing hype, Aquatune adds ridiculous statements about splitting hydrogen from water. That they resort to snake oil salesmanship suggests that they know very well they didn't get the basic idea to work right. A pity-- I'd really like to see the idea work. Oh well, throw this one on the list of busted mods.
It will work best on dry hot days under heavy throttle use and highway speeds and it only takes a small amount of water to have some gain. Too much water and you cool the combustion too much and don't burn completely. If you add some methal alcohol to the water it helps to foam and adds some energy to the combustion process.