This will help reduce stresses on your downpipe/exhaust, and also reduce wheel hop (which can kill your transmission/axles/lots more). Some important information when picking a mount durometer: Generally speaking the higher the number, the stiffer the urethane insert is. The stiffness levels do NOT affect strength or longevity. A 62A mount will last just as long as a 94A mount. Neither of which is stronger or weaker.The stiffer the mount, the more vibrations you will feel while driving. This is our recommendation for urethane selection. Higher than stock HP or light autocross car - 70A. Weekend drag racer - 88A. Dedicated drag race car - 94A.