PFF76-423BLK uses our Black 95A durometer material for heavily tuned vehicles or Motorsport use. An increase in NVH, usually at idle, should be expected when stiffening the connecting mount between the engine/transmission and chassis. The harder the material used, the greater the NVH transmitted. Fits models with a factory-fitted Limited Slip Differential (LSD). For non LSD models use PFF76-421BLK.