Ratio of 50/50 Water-Methanol to be injected

[xga]

From what I've read on here, it seems as though 15% is the general amount of water to be injected in relation to fuel flow. Should this percentage increase or decrease if I use a 50/50 Water-Methanol mix or should it just stay the same?

I know it will probably be difficult to give an exact percentage due to the number of variables to consider, but a ball park figure would be a good starting point.

Thanks in advance.