I really never get much over 25 psi
while towing, so I was turning it on at around 10 and full on by 45psi. At the track it will be more like you described.
For towing if you set off egt
you need to have it coming in a bit before things get too hot otherwise its playing catch up. But still needs to come on in a curve that does not start to low.
The issue is when you look at what many recommend for flow rates they are factoring a 25/75-50/50 mix meth/H2O. With straight water you have : more of it and no extra meth for fuel.
What is your max boost with the way you are waste gated that you see at WOT
If you are going to reference off boost you still need to go off what your engine will produce as you are otherwise pumping in too much water if you try to use it all at a lower boost or shorter curve.
Given a boost max of say 60 I would start at 20 which with a snow controller would be 10% flow capacity and then you can try in small stages dropping the starting ref boost to a lower psi
point. You can also try dropping the max psi
ref point and see how low it can take full water. If you are able to drop a significant amount then you could look at adding more nozzles. the stage 3 controller gives you much more control and options in tuning.
The only thing I get concerned about with water only is that I think it may be possible to add enough water to actually decrease power but not have noticeable quench from SOP or listening. That is why I always think it best to error on the side of a decent safety margin with less water.
I am getting ready to try a Cooing Mist setup with this new build in my X. I have heard very good things about them and their pumps. I will be using a multi stage controller. That way I can have a low volume stage with small jets for typical cruising to gain some mpg
and keep things clean. Then have the larger second stage to come on with heavy towing or hard driving WOT
etc.. I liked the snows stage 3 controller but never upgraded to one as I hated their pumps. I use to run a 25/75 but have since decided it would not be worth the risk given how much $$$ goes into these builds.