Good sound. I also have secondary cats removed on n54 pipes. Sounds like you have a bit of wastegate rattle there.
Montego Blue E90 335i
7" VRSF IC | OFT Tune | DCI | RB PCV | Secondary CAT Delete & CYBA 3.75" Tips | M3 Front | CSL Trunk | 19" LC Dyna Wheels | KW V1 | AA CP