My setup -> 2D kit, 0.5mm + 0.6mm dual nozzle setup, up to about 350 cc/min water injected (currently distilled water only, no alcohol) at redline 7500rpm. Water is about 25%-30% of fuel, injected pre blower (non intercooled Eaton M45 spun to 16K rpm). I am running 10 psi boost, water injections starts at 3 psi.
On the dyno for the final tune of my MX-5 we were tuning for 12.8:1 AFR (it did the max power there) indicated on my TechEdge WBO2 wideband with the water injection on just like with the water injection off.
I didn't notice the injected water (water 28%-30% of fuel) changing the wideband AFR readings
These talks of 12.5 AFR being indicated as 10:1 on the wideband O2 seem being bogus!
The EGT sensor is in one of the exhaust runners - as close to the head as possible (about 1 inch from the head).
My EGT were around 1200F (~ 650C) at 10 psi, 7500 engine rpm.
The intake air temperature sensor is in the intake manifold just in front of the runner of one on the cylinders (it measures the temperature of the air just before mixing with the fuel).
The intake air temperature at cruising on the dyno was 130F (~ 55C).
With water injection turned off at 10 psi of boost the air temperature was raising under boost to over 260F (over 130C).
With the water injection on the intake temperature raised only to 160F (~ 71C)
The ignition timing at 10 psi boost/7500 rpm was about 25-26 degrees advance
My power went up from 100 hp at the wheels (the stock power of a '94 Miata) to 190 hp at the wheels with the current setup (stock engine, never opened, 104K miles on it).
I am going racing this weekend
Time to hug some curves
Next step is probably putting bigger water jets and increasing the water flow (probably above 30% water of fuel)