I personally opted for the Catted Front Section with Resonated X Pipe and F1 Race Mufflers on my former E92 M3.
It sounded absolutely bombastic with a notorious wail around 4,000 RPM that I've yet to hear properly replicated by other exhaust systems. The noise level got much higher as you crossed 6,000 RPM. Drone was present, but limited. It is a very daily-friendly configuration.
I have not curated any non-resonated X pipe configurations.
The S65 will tend to rasp when removing resonators and pairing with an aftermarket rear muffler combo. I personally would not recommend it unless you have sound tolerances that are higher than most.
Specifications
Hand Made in Italy
304 ASIS Stainless Steel
HJS Racing Metallic Catalytic Converters
Straight through muffler designs at all Sound Levels