Quasi-Custom Water Nozzles, PWM and Pyro

I have a Cooling Mist DMS and pump at home waiting for me.

My truck isn't going to see much over 400 HP on fuel ever, but it is also non-intercooled. So I'm planning to fumigate pure water on a very frequent basis.

To that end I'd like to use a PWM to control the pump with the DMS's 0-5 volt output, but I'm not too eager to buy one of Cooling Mist's.

1. Anybody know of a good PWM to use? Something like this should work great, right?

2. The second big question is what size of nozzle to use. Could I get away with one size nozzle for my power levels, or am I going to need to run multiple nozzles to provide decent atomization at various pump speeds?

3. I would like to use my thermocouple for input into the DMS as well as my pyrometer. Anybody know of any inexpensive splitters to let me do that?

Thanks for any help folks.

I think you'll run into a problem with un-atomized water at very low pump speeds. Other than that, why not just 'arm' each stage/jet independently?

I think there are two ways of doing this.

First way is to control pump speed with a PWM.
If I go that route, I have complete control of flow rate. But since I'm putting various amounts of water through a single nozzle, I might have atomization problems.
To alleviate that problem I could use a solenoid or two to run a couple different sized nozzles; open up the little nozzle for low pump speeds, and then swap to the big nozzle for high pump speeds.

The second route cuts out the PWM entirely, and just uses solenoids to open up different nozzles while the pump runs 100% the entire time. That sacrifices some controllability, but I could still do something like alternate three different sized jets to have seven "stages" of flexibility.

What sized jets should I be using in any case, though?

Jet size will be dependent on PSI and amount of water you want to inject.

So how much water do I want to inject into a 400 HP 1st gen with no intercooler and a stock turbocharger? I start seeing excessive EGT's at 20 PSI and can get up to 35 PSI of boost pressure. This is the pump I have.