schmoell:

My two AMGs had this very loud sound when starting the engine (after 2 sec it was over).  I always found this more than embarrassing, because - more often than not - I had to leave at 5am. I very much hope that AMG has changed this. 

For a lot of cars that initial loudness is due to the car trying to quickly warm up the cats.  So rather than particulate pollution they create noise pollution.  My GT3 RS is insanely loud at start up (no valves) then quickly quiets down as well.  I love my exhaust but it is embarrassing when I start it up early in the morning and my garage faces my neighbor’s master bedroom Smiley