1-3/4'' header pipes flow in a tapered 3'' to 3-1/2'' turnout megaphone37'' L with 3-1/2'' billet end capIncludes performance baffleMade in the U.S.A18 mm to 12 mm sensor bung adapters not included. Must be purchased separately if requiredDoes not include O2 sensor port plugs for non-sensor applications