Made in our softer Grey 65A material, PFF85-420R is intended for standard diesel vehicles. For petrol or modified diesel vehicles, please use PFF85-420. A small increase in NVH, usually at idle, should be expected when stiffening the connecting mounting between the engine/transmission and chassis. The harder the material used, the greater the NVH transmitted. Please have a look at this quick guide on how to fit PFF85-420 and associated part  PFF85-505