OregonDmax: I always heard the factory box was pretty good until 500hp, not saying your wrong, but can you cite some info on this?[/QUOTE]
Yes but that only applies to the 06+ models with the round filter. The 01-05 have the same airbox as the half tons basically. They are very restrictive hence why people cut them up to improve flow, in the end they still aren't that great.
I dropped 50* in egt's cruising at highway speeds going from stock to aftermarket CAI on my 02.