I saw thins thing under my air box, but I don't know exactly what it's for...
It's black/gray and has an oval opening. There are pegs for the air box to set in.
What is is and what are all of the purposes of it?
See pic below.
Can't tell to well from that picture, but I think it is the air intake. From there the air passes over the PCM to cool it and then through the filter. The OEM setup is essentially a CAI.
That is the air opening to the airbox... Supposed to suck in cooler air from the front of the car.. .. You would not want to pick up the hot air from around the engine compartment.