When to activate Water injection?

[Philip]

Hi all,

Ive just about finished installing a Paxton supercharger onto my rover powered cobra replica. Im going to be boosting it by around 6 psi and want to use water injection purely as a precaution. I dont think i'll need it but better safe than sorry. My question is that im going to reprogram my ecu to control the switch on point of the water. As the ecu uses manifold air temp, revs, manifold pressure etc, i can use these to form a switch on point. So what sort of temp and boost level should i be looking for the water to come on at? My comp ratio is 9.75, its a 3.5L V8 if thats any help,
Phil