thank you for the pics and your efforts so far.
i don't think the temp of the crossover pipe is a big deal. i would rather have more throughly mixed air/water than a cool pipe. tho maybe put it after the bend so water doesn't land on the outside curve of the pipe.
the other thing i was looking at was to use a
pressure switch and solenoid so the pre turbo nozzle didn't come on till near max boost . that way it didn't run while at cruise to save water usage (post turbo nozzle is still used). pre turbo is probably not all that important at low boost. that will vary depending on motor of course.
also it means pump pressure is up high for better water spray which will be better for the turbo impellers.
what will be interesting is how LITTLE water you can get away with useing to get an effect.