Few aftermarket kits are deisgned to acutally place the filter in an area where there is "cold air". But, having installed a couple of these, from real kits to DIY, the main thing you get is a much better sound from the engine under full throttle.

The typical airbox in a newer car is designed to eliminate intake noise. Adding the cold air kit (at least on v8 cars) brings it closer to the whoosh sound you get when you step into the 4bbls on our Mopars.

I wouldn't personally spend $250 just to make the car sound cooler under WOT, but I have no problem spending $1 on a piece of PVC, and $40 on a K&N cone filter to get the sound.