I just finished opening up my mail box on my 07 S today. I also found a good misting spray nozzle and installed that. Now for the bad news, the GM water pump used in the windshield spray tank is a joke -- tested with it and all I got was short pulse of next to no pressure, it was beyond pathetic.
So I'm searching for a high pressure water pump for 12v DC and the only thing I've found is a Shurflow which can only do 130 psi max. After searching the net some I'm finding out that true mist systems (multi-nozzle) are running at 800-1000 PSI, weigh A LOT, very large, and some want 230 v 10amps+
I'm thinking I could probably get away with 200 psi unit for a single mist nozzle, but there are none to be found for 12v DC.
So in a word, external water mist on IC doesn't appear to be a workable reality until someone can produce small efficient light weight pump.
I've been made aware of a "yet to be released" alternative ... stay tuned.
How about this unit? I'm thinking about using it on one of my cars.
New High Performance Rapid Cool Radiator Mist System