The MMX Billet Differential Insert Kit is a simple yet highly effective upgrade for F-Series BMWs (F2X & F3X). Designed to fill the voids in the factory rubber diff mounts, these precision-machined inserts limit movement under load to maintain suspension geometry, sharpen rear-end stability, and deliver a more connected driving experience.
BMW’s standard rubber differential mounts allow unwanted flex, which can make the rear feel vague during acceleration, cornering, or when launching hard. By replacing these voids with CNC-machined billet aluminium inserts, the MMX kit reduces deflection and helps the diff remain firmly in place — without adding noticeable NVH (noise, vibration, or harshness).
Installation is quick and straightforward, taking less than an hour, and the upgrade is fully reversible if required. The result is sharper handling, improved traction, and greater confidence behind the wheel, especially when paired with aftermarket suspension upgrades.
Key Features
CNC-machined from durable 6061-T6 billet aluminium
Fills voids in OEM differential rubber mounts for reduced movement
No increase in NVH — cabin refinement remains unchanged
Helps maintain correct suspension geometry under load
Improves rear stability during launches, acceleration, and cornering
Quick installation in under an hour, fully reversible
Works seamlessly with factory or aftermarket suspension setups
