Though symantics (and we know what was meant), during warm-up the AIR system pumps air into the back of the heads, not the cats. This helps the cats to light off faster. Once up to temp, the air is diverted to the cats.
I have to say that I have been meaning to research this a good bit. We know that Ford doesnt add parts it doesnt need to, but with all the cars out there with cats that dont use an AIR pump, I wonder if the pump was to help do a little extra clean-up on an inhertantly dirty motor.
I would like to find data regaring uncatted emissions output from an EFI 5.0L vs a car coming catted but non-AIR pump equipped.