it has been a while, the exhaust was old, probably the original, patched and repaired several times, after different searchs, and discussions, after talking to many people, including Albrecht Walloth,....
(real old) stock has the nicest sound. Aftermarket is either cheap or stainless. Stainless of course will look great and last very long (if manufactured properly) but stainless has different acoustic properties which usually are "tinnier" than the mild steel of the sock system. So that´s often overcompensated with less muffling and more drone.
I´ve been down the stainless route and am now back on stock.
A matter of taste of course...
Did you recently find a source for a NOS exhaust? Aren't these parts still available from BMW?
I'm sold on that Sound Quality. Listened to it through my headphones (which have been on my head since I bought them)