I installed the PSMCold Air system for several reasons. First, it is a more refined way to get the same effect as the DYI system described in the TDR magazine. My 04 factory system has a smaller fender intake opening than the newer models, indicating to me that the higher output engines need more flow. The PSMCold Air takes air from outside of the hot engine compartment. It includes a baffle that closes off the engine compartment hot air from the suction of the extension hose. The DYI described in the TDR magazine does not accomplish the isolation.
Reading the latest Diesel Power, one technical article highly critizes the "filter on a stick" approach of some of the high dollar intake systems. He said that any system that you can see the filter when you open the hood is not good. Hot air from the engine compartment is not the source of air desired.
The PSMCold Air system was so inexpesive that I also purchased the Cool Blue torque tube, giving me a total system. I really, REALLY like the Cool Blue torque tube. It is quiet and is excellent at insulating the incoming air from the hot engine compartment.
Do any of the systems offer huge increases in performance?? I really have not read any independent test that show anything but minimal improvement. One thing I do know about my choices - cold air can't be bad.