Proper end links may be necessary to fully realize the potential of your anti-sway bars.  Cusco has changed the bushing compound at each joint to provide more stiffness, in some cases, depending on application (drifting versus rally).  By having stiffer links, the energy transfer through the suspension components, particularly the sway bars, is better controlled by the sway bar setting or stiffness.  This twisitng motion pulles on the end links and the hardware holding it all together compresses the bushings.

Another feature on some end links are adjustibility. This allows the distance between the chassis and the end of the sway bar to be adjusted for the desired outcome.