I have only used seafoam once and it was in a 1970 Honda Trail 70 motorcycle. Let me just say that it completely transformed the way the motor ran, despite eating through an old epoxy repair of the carb which required a bit of lead, it worked fantastically. Bike starts up first kick every time, and runs like a top. It has over 15K miles and only does 35 flat out, its seen some use.
As far as these cold air intake setups go, where I live it is over 90 degrees outside right now, there is no cold air. The idea is to keep the source of the air and the path of the air into the engine away from the heat created by the motor and radiator. A complete stock setup with the snorkel between the headlight cover is a pretty damn good idea. Not saying a nice heatshield and cone filter couldn't be just as effective, but if it isn't sealed at the hood completely then it is useless; it will just act as a vacuum and suck all of the hot air from between the engine and rad. Also, check how hot your intake manifold gets after the car has been running for a while, all of your efforts to keep the air temps ambient are pretty much snuffed out. The inside that thing is like a friggn' oven.