Using water injection (or water / methanol and even straight methanol) has advantages to building more power. It eliminates knock (detonation) which allows for higher PSI boost on the engine safely.

The water / alcohol cools down the cylinder temperatures. It also helps clean away carbo deposits which can cause hot spots leading to engine failure.

I use the AQUAMIST 2D system with a DDS3 in cab controller/gauge. This is in my opinion the very best water (alcohol) injection system out there. A little more spendy but it does so much more than lesser units.

It uses a 100psi pump and the system is under 100psi the entire time (pre-pressurized system) so there is absolutely no delay in delivering the fluid to the injector nozzles.

I currently use (1) 1mm jet that delivers approximately 310 cc which translates to about 10% fuel ratio using (6) 550 cc fuel injectors. It is set to inject when boost is above 15.5psi.

A double advantage in this system is my HKS fan controller includes a sprayer function that will sub-control the same system but re-route it (if not under boost) to 3 sprayer nozzles. 1 for the radiator and 1 for each side mount intercooler. This helps resolve intercooler heat-soak if doing a lot of high boost runs.

This was the setup when I had the FMIC installed:

1mm injector, flow sensor, and 30cc accumulator tank. The manifold pressure switch and tie in to sprayer option is above where the headlight goes. The other wire on the intercooler pipe (to the left of the injector nozzle) is the intercooler temp readout sensor (out readings).

Below is the current setup after moving everything due to changing back to SMIC (and ditching the FMIC). Everything had to be moved from below due to re-installing the intercooler to side mount. It all fit behind the passenger headlight after some careful modifications. Pump and tank stayed the same (under the main circuit break panel, passenger side).