Pdx peeps: looking for something, and need recommendations

[Amskeptic]

I have no idea what an intake air plenum is!!

That is why you are here. We answer questions exactly like yours.

Intake Plenum

All that air bashing in through the fresh air grill has to be tamed and it has to separate out the water that may be mixed in with it if you are driving in the rain. The plenum is just a big room immediately behind the incoming air grill where rain or wash water hits the walls and drains out through a plastic drain tube. The outlets are positioned high so they pass only water-free air. The incoming air can be shut out by closing the doors actuated by your blue lever(s) on the dash. You see the back wall of the intake plenum just above your kick panels. There is some science involved in the design of the plenum and outlets to reduce draft and prevent whistles. I wax my plenums and underside of the car and underneath the spare tire and the little compartments under the front seats because I no longer have a life.
Colin