Water injection is a guard against detonation. It doesn't lower the charge temperature and doesn't do anything about heat soak.

If one were to add only one ITR cam to a motor with a JRSC'd motor, it would be the intake cam. With just the exhaust cam you wouldn't be able to suck any more air into the motor but some of the boost would creep out the exhaust valves unless you worked on dialing out the overlap. With a supercharger you want lots of lift and semi-long duration on the intake, and less lift and very low duration on the exhaust.