Tuning: EGTs after adding water injection

[Andrew]

I have recently installed a WI system and am wondering what kinds of effects I should be seeing as far as exhaust temperatures.

This is a "stage 4" WRX, using 91 octane fuel and injecting pure water. Currently, water delivery is ~15% of fuel volume at maximum flow (measured), and is metered by the Aquamist FiA2. My tune is basically a 91 octane-only tune with the WI added on top of that.

Under boost, my EGTs peak close to 1500 F. As I understand it, I should be seeing significantly lower EGTs with water than without. But this is not what I am observing.

So, I have a couple of questions for those of you who have experience tuning WI successfully.

1. What EGTs should one see when adding water to a gasoline-only tune?

2. How much water (or water/alcohol mix) are you using? Details on how you calculated and/or measured this number would be great.

Andrew