My muffler came with 2 baffles. One a perforated disc that fit between the mid pipe and front of the muffler. A noise (and power suppressor) for the Europeans. The other is a ring at the end of the exhaust. The latter is held on with a screw under a plug on the muffler. I took the ring off and it was too loud for me, so it went back on.
BMW Motorrad USA customer service: "We make superior motorcycles and continue to improve them."