The poly bushings reduce the compression found in rubber. Rubber bushings compress based on the durometer or hardness. The rubber has a durometer of 80 vs the poly durometer of 95. The poly will never dryrot and with the endlink bushings it will provide a better than stock performance. The kit also allows you to save money by giving you a way to rebuild the endlinks which can cost $30 alone. Ride quality is not reduced but handling is much improved. After installing the kit you will notice a difference in reduced understeer as well as all around handling.