I use the snow stage 2 kit. I have nistune tuned for 17psi without water injection. This is my low boost setting. I run a smidge under 20psi on high boost with water injection, same tune, no knock.
Looking at getting a safeguard of some sort, but for the time being, when I do mountains or after a bit of boosting I switch back to low boost until I can check the water level in the tank. I only have the small snow res, located behind the glovebox. I am always topping it up, paranoid about another grenaded engine lol