While AMG's and Brabus sound crazy to begin with, Mercedes engines often have a quiet growl, perhaps especially their V8's and V12's. One way to wake the sound up, especially with the m278 engines, is to delete the center resonators.
This produces a nice deep boat like cold start, great sound on revs, somewhat quiet idle, and very little resonance.
UPDATE
I finally did a video on this with recordings at highway speed for people to discern if it is a livable mod for them.
