Torque cones are used to create a higher velocity of exhaust flow in the exhaust pipe and creates an anti-reversion effect. The value of anti-reversion is a cleaner air fuel burn combustion and a cooler running engine. The larger diameter, (gold) offer excellent mid range performance, killer top end and lots of sound. The smaller, (silver) enhance low end performance and have a great mid range as well. Still less restrictive than running baffling, top end is still strong. This set up also has an aggressive sound, but slightly less than the gold chambers. Install whichever set of chambers best fits your riding needs using the same hardware used to retain the baffles