While fanatically browsing around the relatively new speed shop that opened just up the street from me (they cater to the serious racers - special hours during "build your car" season - I live 1/2 mile from a NASCAR track) and ogling the $400 brake calipers, I noticed a shelf of molded ductwork. These were mostly designed to be brake cooling air inlets. Several types were made to mount in the outer sheet metal with one or two round outlets. One strange looking one caught my eye. It was a trailing arm mounted duct for cooling rear brakes, with a rectangular opening about 4" by 10", gracefully swooping to about a 3" round outlet. $30 later it was mine...
I discovered that it fit almost perfectly over the large holes in the sheet metal behind the lower grill. So I took out the Dremel and removed the plastic blocking the fins on the starboard end of my wonderful perfect new center lower grill. I had to warm up and bend the edges of the duct flat to fit better. Three quick holes in the duct and the sheet metal, and some metric T-nuts and bolts, and it was mounted. I used a 3" by 24" (longer than necessary) air intake hose from a local auto chain (about $7) to get from the duct to the inlet I am using on my coupe, which came off an 87.5, but should be the same on any wraparound style bumper small Audi. It has a larger "in" opening than the stock one on my car.
This probably will be very difficult to do on a car with intact A/C, since I am pretty much using the space previously occupied by the compressor for my hose.
Of course my car is now hugely faster, corners better, gets better fuel economy, etc.