The C63 AMG's exhaust is just about perfect, I always change the exhaust of my cars, even the family SUV's, but when I got the C63, the exhaust was so perfect that I just couldn't make myself change it. Even though adding an X-pipe similar to the Accufab would wake the car up more but the factory tuning of the sounds is just so perfect for anything that is driven on the streets most of the time. Then add a cheap tune to reclaim the lost HP from the factory's detuning and you have the best bang for your 70 grands on any high quality (that excludes the CTS-V) high HP (510) family sedan.