Aquamist(aquamist.co.uk) sells a high quality water injection setup. Most of the guys that use water injection that I have talked to have gone with Aquamist. One of the cool things is that you can go that the gas station, buy a gallon of windshield washer fluid for a buck and use that. Why would you want to run that? Read the contents: 49.5% water, 49.5% methanol, 1%dye. Yeah, dumping water into your engine might seem like a bad thing, but it really isnt. The water is injected as a fine mist into the intake. This mist vaporizes almost instantly, absorbing a lot of the heat. The methanol is even better for this.As you know lower temps=more power and the ability to run more boost.
It is kind of like running a tank full of race gas every time. I have heard very good things about propane injection too, but I am not very familiar with it.