The Bilstein B8 Performance Plus rear damper for the 2011 BMW 335i xDrive Base is a 46mm monotube unit with gas-pressure construction, built for cars that already run lowering or sport springs. The BILSTEIN B8 is BILSTEIN's sport shock absorber for lowered cars. Shortened by design to keep the right spring preload and travel with lowering springs, the yellow monotube delivers sharper, more precise handling. Choose it over a stock-length damper if your 335i xDrive is already lowered. Bilstein says to use the B8 when the car is lowered and the B6 on OE springs. Bilstein also states that Performance Plus dampers carry application-specific valve settings tuned for paired lowering spring kits, so the damping is matched to the spring rather than generic.
If you are fitting this rear shock, owners on user forums describe lifting the lower control arm to compress the unit so it can be pulled out of the upper mount, and the trunk trim has to come off to reach the top. Threads on strut swaps on these chassis list a 17mm socket, a 6mm hex, and a torque wrench as the core tools. Search terms buyers use include "B8 Performance Plus rear shock 335i xDrive," "lowered E90 335i xDrive rear shock," and "Bilstein monotube lowering spring rear damper." Confirm fitment against the manufacturer's vehicle selector before ordering.
The manufacturer states the B8 is designed to work with your existing lowering or sport springs, which do not need to be replaced.
The manufacturer states B8 dampers are shortened for lowering springs ranging from 0.8 to 2.0 inches.
Owners on user forums report that the job is manageable at home with a jack, stands, and basic hand tools. Compress the shock by raising the lower control arm, then pull it out before it re-extends, which is easier than fighting it with a nut and bolt alone. Expect to remove the trunk liner or trim to reach the upper mount, and plan to clean and inspect the upper mount hardware when you reinstall. Torque the fasteners to the manufacturer's specification.
