60707 is a 3" diameter optional resonator that can be added to 140643 and 140830SB for additional sound attenuation. Built from premium T-304 series stainless steel for durability and long life. Ultra-smooth mandrel bends ensure maximum flow & power and precision Computer numerical control (CNC) manufacturing ensures an accurate fit. We strive to provide you with the best quality products and stand behind our resonators with a Million-Mile Warranty.