PFF76-423 uses our Yellow 70A durometer material and is suitable for standard or mildly tuned vehicles. For track/tuned models use PFF76-423P. A small 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 PFF76-421.