Significant noise reduction is what you can expect with these Exhaust Turndowns with Cone Inserts from Dynatech. The turn down is expanded to slip over collector outlet or tailpipe (but welding or bolting is a recommended mounting method). Greater sound reduction can also be achieved by directing the outlet away from meter or sound test point. U-tab mounting hardware is included. The mild steel turn down with T304 Stainless cone insert is available in 3.00'', 3.50'' and 4.00'' sizes.