My water injection is basically in the same place as Appie's although I run a different size jet, the water injection is mapped against boost pressure and act temperature as such mine is only protection against detonation.
The methanol is mixed with water as it offers additional properties including the fact that it reduces the ease at which the water will freeze during cold winter months.
I personally do not think you see any gains unless you are using the water injection to overcome failings in your induction cooling