When to activate Water injection?

[Philip]

Hi,
no im not using peak and hold as my injectors have external resistors so this is not needed. So what your saying is fire the water valve when the injectors are fired? So do you then increase water pressure to tune the amount of water or do you need to increase/decrease the Pulse Width to tune? Just had a quick calculation and all my injectors will fire 1500cc/min of fuel, so If I fired a 150cc/min nozzle at the same time as the injectors then I would get 10%, Yes?
thanks for all your help,
Phil