PFF1-1130R Lower Engine Mount Insert is made in our softest Red 65A durometer material, specifically for Diesel models, helping to limit NVH transmission. Designed to fill the voiding in the OE rubber mount, it smooths out gear changes by stiffening and supporting the often perished rubber bush, which is common for failure on tuned vehicles. This will provide a more precise and settled transmission response during acceleration and deceleration. 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.