For my 1st mod I went with a turbo-back, cheapo ssautochrome single tip exhaust. I also did a DIY FCD at the same time. 1st impressions: it's LOUD as hell! Definately pulls better in the upper rpms. The exhaust quality seems pretty damn good, the fit was excellent. There is pretty much no noise suppresion from the muffler; it's not much bigger around than the pipe.
I also removed the airpump since there is no longer a need. I made a block off plate. I do have a question, it said "do not remove pump, no oiling" on the air pump. I thought the air pump had nothing to do with the oil injection system, am I wrong?

 

It doesn't. its not supposed to be removed because of smog. And the no oiling part means you don't have to oil it.

 

If you have an S4 turbo (87-88), you will get boost creep bad unless you port your wastegate.

 

Well, thats a relief. Where does everybody get the boost signal for the boost sensor with an air pump blockoff plate installed?