As well as their Suspension Bushes Powerflex also offer these high performance upgraded Polyurethane engine & gearbox mounts.While stock mounts will be designed with limiting Noise, Vibration and Harshness in mind this isn t necessarily ideal for the extra stresses caused by spirited road or track driving.An upgraded engine mount from Powerflex will allow for less flex in the engine mounting resulting in less engine movement while still offering superb sound damping.This in turn will mean less wasted power, sharper gear changes and less stress transmitted to the downpipe.Please note a number of different compounds may be offered.Red compound mounts (the product code will usually end in R) are the softest on offer. They are ideal for diesel engines. The soft red compound will soak up the most NVH. Powerflex recommend these for diesels (which produce more vibration) but they may still be used on petrol engines. In many cases they are still harder than the factory engine mount and the soft compound will soak up more noise and vibration than the stiffer compounds.Yellow compound mounts are the middle ground. Powerflex don't normally recommend them for diesel as a lot of NVH will be transmitted.Purple compound mounts (the product code will usually end in P) are the stiffest compound short of the black series. These are normally recommended for track use. Additional NVH will be experienced, and they are not normally recommended for diesel engines.Black series bushes may be available for some cars. These use the hardest compound Powerflex make and will transmit a lot of NVH, but will also offer the most rigidity short of a solid engine mount.