Refer to the YouTube video below, and you will have a better understanding of the working principles of the catalytic converter and tailpipe. Thanks to Automotive System Description YITAMOTOR high-flow catalytic converters increased exhaust flow allowincertifications:OBD-II , Federal EPA, Non-CARB, material:Stainless steel, restricted states:California, new york, colorado, maine, fitment type:Direct replacement, inlet type:Loose Flanges, outlet type:2 Bolt Welded Flange, engine:4.2L, oxygen sensor ports:1, substrate:Ceramic, interchange part number:55476, 645878, 50365, 19100, warranty:5 years or 50,000 miles limited