Trust me. It works to a certain extent, but not entirely. Our PCM'* are too smart for that. Aquamist won't tell you that, because they're trying to sell the kits. Your PCM needs time to react to the apparent temperature change. It gets worse, too. Your PCM is programmed to watch the IAT AND the MAF. You'll be injecting after the IAT, so it will think you're running warmer than your intake actually is with water injection. It will deliver less fuel than it needs. Now there'* 2 reasons why your PCM will try to run you lean under boost with water injection. So you have to trick your IAT, also.
All these systems are inter-related, and it'* just too damn much of a pain in the *** to deal with. Then you have to fill the tank. Filter the water.....worry about freezing, or don't run it in the winter. Worry about hydrolock (and yes it CAN happen even if you're boost activated).
Are you starting to see the light? I'm the only one here running it, and I'm telling you NOT to. From my own experiences.