Pretty much everything has been covered. Like Paul said, I have the Snowperformance Stage II water injection kit with dual nozzles, 60ml/sec jets and a mix of ~ 33% meth, 99% purified water with a max boost of 14psi.
Here are some install pics:
Looks stock:
Here's the water pump:
Here you can see the water tank:
Tank, controller & lines
Pass nozzle:
Driver's nozzle
I didn't like the kit when I had the larger jets (both the 100ml & 175ml) and I was loosing power; too much of an octane boost. Now I have 60ml jets and the car runs alot better. The 2qt tank will last me about the same as one tank of gas.
Unlike charge cooling, water/meth serves a dual purpose. The water cools the charge while the meth is an octane booster (water also acts as an octane booster since it doesn't burn). This is where the big hp gain comes in. Since it increases the octane, you can add more boost and more timing without detonation. This is where bigger jets and diff water/meth ratios come into play
I'm not interested in squezzing the most HP out of my Esprit. I just wanted something to cool the charge and this water kit with small jets worked for me.