Designed with trackdays in mind to replace the tear-prone soft rubber factory transmission mounts, a common cause of knocking, mis-shifting and over-revving. Fits RWD vehicles only. Made  using CNC machined Aluminium Caps with captive securing bolts and a Purple 80A  Durometer polyurethane body, they increase stiffness over OE by 260% for razor-sharp  engine response.They are also the perfect accompaniment to our  PFF5-4650  Tuneable Engine Mount  on E36/E46/E9*  models.