Bimmerpost member dd1981 took videos to compare what his F30 335i sounded like before and after I putting on the M Performance, plus another video after breaking it in with 1000 miles. Listen to the actual difference in sound on these videos:

2012 BMW F30 335i Stock Exhaust. Warm Start.

With M Performance Exhaust, 2012 BMW F30 335i, Semi Warm Start and 4k Revs.

After 1000 miles.