Hi as above i have bought an aquamist pressure switch to un my intercooler spray but where can i fit it and how? cheers

 

There is usually a hose barb with the Aquamist switch which you can run a bit of vacuum line from to a T-piece which you can put in a vac line coming off the inlet manifold. You could use the one that goes to the MAP sensor, boost gauge, whatever.

IIRC the switch is normally closed until the pressure target is hit. So you'll probably need a relay, wire etc.

Spraying only on boost is not necessarily the best for water consumption and effective cooling - there is an Autospeed article on this.