I have been playing with this for a while. I am still working on it. I covered the fake vents. And made a partial lower grill block. I based these on the "Worlds Fastest Civic". They made from plexiglass, spray painted black and held on with doubleback tape.
I still want to make an air dam. I am considering using either plastic lawn edging or aluminum flashing, and attaching it with pop-rivets.