Water Injection for NA Cooling ...
(the following is from http://en.wikipedia.org/wiki/Water_injection_(engines)

"In a piston engine, the initial injection of water cools the fuel-air mixture somewhat, which increases its density and hence the amount of mixture that enters the cylinder. But the greater effect comes later during combustion when the water takes in significant amounts of heat energy as it converts from liquid to gas (steam). This increases piston pressure (torque), reduces peak temperature and resultant NOx formation, and reduces the amount of heat energy absorbed into the cylinder walls. The duration of combustion is said to be longer, preventing detonation. In aircraft engines the cooling effect allows the mixture to be run leaner at its best-power setting.

Fuel economy can be improved with water injection, although the effect on most engines with no other modification, like leaning out the mixture, appears to be rather limited or even negligible in some cases.

Some degree of control over the water injection is important. It needs to be injected only when the engine is heavily loaded and the throttle is wide open. Otherwise injecting water may simply drown the engine and cause it to quit."

Several of the vendors have kits for water/meth injection which include a progressive controller. Light throttle = no water, Heavy throttle = some water, WOT= more water.

The potential is 15 to 20 HP increase with -20 windshield wiper fluid during WOT on a 2.4l VVT NA if you do it right.