[AMF]

Running a water/meth injection by itself won't bring you any more horsepower, but the ability to alter the tune to a more agressive state will.

Generally speaking, if you're running 14 psi in the South Florida heat and you want some added assurance that you won't get detonation when you run uphill, in 4th gear and low rpms....then you can add a water/meth injection.

You can do the same thing with a small nitrous shot. The rapidly expanding gas helps to reduce intake temps quite a bit. You see this A LOT with ricers who love to run 30+ lbs of boost with turbos and such. They'll throw on a 50 shot, not necessarily for the power (though it helps) but more so they can cool down the charge and go after more boost.

Cooler intake temps help guard against pre-ignition and detonation.

A water-meth kit will allow you to safely run 12 psi where maybe it was only safe to run 8 psi before.

You might also be able to get away with more timing, where it was risky before.

Thus you're able to make more power, not from the water/meth itself, but from the ability to add more air/fuel and more timing by cutting the likelihood of pre-ignition and detonation.