[hockenheim]

My 98 base also had an exhaust rattle. This was with an aftermarket Dansk sport exhaust. It only happened when the exhaust was cold. It turned out that the perforated "shields" in the exhaust tips (what is their purpose anyway?) were loose. With some wire and the Permatex muffler repair paste I was able to secure them and the rattle hasn't returned since. I am not familiar with the S muffler but you may want to tap the various components of the exhaust system including the clamps with a rubber mallet with the car off to see where there is a loose part