My case was slightly different. I have a 2011 E90 335d without the sports suspension. I was unhappy with the OEM dampers. I replaced them early on with the Bilstein B6, but they would not work with the sports springs. I think it is maybe the B4, can't remember. The B6 were a great improvement no doubt, but now I am shortly going whole hog and replacing everything underneath almost, so my B6 with about 5K miles will be going on the auction block. In summary, I have been happy the the Bilstein B6. Even took them to the HPDE at Summit Point in September and they performed quite nicely.
Mods-Etc: Quaife LSD w/VAC finned diff cover, M3 Rear SF Bushings, M3 sways & OEM Susp Front/Rear Cmpnt Kits ('cept strut brace), GC Caster/Camber Plates, AC Schnitzer M3 Sport Springs, JRZ RS1 dampers, JBD 100%, Goodrich SS brake lines, non-stggrd APEX ARC-8 18" wheels with Nitto Motivo tires (winter OEM 17" wheels and Blizzak LM-25).