SuperPro's rear differential center support bushing drastically reduces the deflection of the OEM rubber differential mount under changing loads - especially rolling on and off the throttle. This offers benefits in throttle response and in manipulating the cars cornering attitude with the throttle as the car will react more quickly and directly to changes in throttle input. In addition the SPF3404-70K offers a vastly extended service life over the soft rubber OEM piece backed by a lifetime warranty. Looking for a more motorsport-oriented version? See our SPF3404-80K; the higher durometer version of the rear center differential mount.