anyone know how the Sport Exhaust on the 911 Carrera works. There is a switch that flips in "off" (light comes on and it does get a bit quieter).

I have a new 2004 911 Carrera tiptronic. Not sure why the dealer had an untitled '04 that long, but regardless, its mine now.

I'm just curious what it does. I assume the switch closes a valve and pushes the exhaust through an extra muffler, but I don't really know.