well on the subject of cooling ideas. There is:
air-to-air
water-to-air
co2-to-air
injection
The first three all involve heat exchanging. Which is a very efficient idea. Air-to-air requires quite a large exchanger since the outside air is, well, outside, and really not that cold. These do help with power adders, but it takes a lot of force to push air through these things. People with boost usually see 2-3psi drop in boost. Using this in a naturally aspirated scenario would decrease power.
water-to-air is more efficient than air-to-air and the nice thing about this is you can virtually put it anywhere. There are usually 4 components to this system. The heat exchanger, which is mounted where it can get outside airflow, the pump, the reservoir, and the intercooler. The intercooler can be mounted anywhere between the filter and the cylinder heads. Some people incorporate them in to the intake manifold itself, where it sits between the throttle body and the heads, and air passes by it at this time. Others make a box, similar to the stock airbox, where air passes through it at this time, and then enters the intake, enabling you to use a stock intake manifold. The reservoir can hold ice, water wetter, whatever you want. It is then pumped through the heat exchanger and through the intercooler, rgeatly decreasing intake charge temperatures while maintaining efficiency, since a smaller intercooler can be used.
Co2-to-air can be a good naturally aspirated power adder, and of course, works very well with power adders. It works by placing an aerodynamic 'bulb', similar to a teardrop shape, in the airstream. There is a small steel line that runs in to and out of this bulb and passes co2. When Co2 turns from liquid to gas it gets to freezing temperatures. The bulb frosts over, the air passes around it, and is instantly colder.
injection can involve gas or liquid. Gas being nitrous, and liquid being water, or more commonly, methanol. Nitrous is pretty obvious in its workings. But do realize that nitrous, by itself, is not combustible. It only adds to combustion what air does, just in a denser sense. And since nitrous also gets cold when turned from liquid to gas, while addingcombustability in the chambers, this is a pretty common power adding setup for boosted vehicles, since it cools the intake temps and also gives a boost in power. Liquid is done by injecting water or methanol in a very very fine mist in to the airflow. Methanol also becomes cool when evaporating from liquid to gas, but on a smaller scale, since it is naturally a liquid to begin with and does not require compression to become. This would be the most efficient of all of these options, since it does not obstruct the airflow, pressure drops are minimal and boost is maintained.
-Thomas