[sambeeb]

An intercooler spray has worked brilliantly for me but I had some pretty specific dramas I needed to overcome. My intercooler is a tiny 20 by 30cm oem side mount. It would heatsoak after only 1 or 2 power runs and then inlet temps would hit 80 degrees. The water spray triggers at 1 bar (1.4psi max boost) so you really have to be up it for it to activte which minimises water loss. It takes time for the cooling of the IC to take effect though. If you start with a heatsoaked IC it'll take 30-1min before you'll see any effect on your temps. For sustained running though it will reduce your inlet temps - I had a thermos couple installed into the hot side of my core and the core temps got to 4 degrees below ambient after a good 5 minute flogging which is pretty good. Even for point and squirt style driving it is very good at getting IC temps back down after each full boost event.
Where it really helps is on the start line. I do hillclimbs and the queue time would mean that the IC would be heatsoaked nefore I even started. Now (using a manual momentary switch in the cabin) I can give the IC a squirt or two of water every now and then as I approach the start line and its cool as a cucumber and ready to go.
Incidentally if you really want to make a water spray effective, add a fan to your IC. Whether I'm in traffic, start lines or hammering the car the fan in conjunction with the water spray is unbeatable.
My car has water injection, water spray and the IC fan and now my inlet temps don't top 40 degrees really. I think the changes you see if you already have a quality air to air will be less though, but if your IC is under rated like mine was then it can really help.