i dont know what this will count for but here goes:
most car manufacturers design the engine bay is such a manner as to provide the best underhood cooling by forcing air into the engine compartment, (with a path over the top of the engine and exhausting at the firewall/bulkhead area) - thats why if you look under the car there are lower covers that prevent additional turbulent air from disturbing this flow pattern, forced in the front and vacuumed in the back. so that means the air drawn in by the fan, and forced in by velocity has to pass over the area which most dci's occupy.
so naturally the open intakes are drawing in perhaps a little cooler air, when the car is at speed, but it will also contain heat produce by the engine components. maybe this is one the reason a few folks are staying with the OEM airbox or a CAI.
but then again my car is bone stock so what would i know