These headers measure 1 3/4" O.D and 42MM I.D. These Headers are recommended for 3.4 - 3.8 liter Motors. These headers include the Street Adapter pipe that can be used with the stock exhaust system or aftermarket exhaust sytem that utilizes the same stock mounting locations after the headers. Our headers are made in the USA from equal length, mandrel bent 16 gauge mild steel. All headers maximize flow by utilizing 3 into 1 RSR collectors that are scallop cut. These headers are designed as a simple bolt on with no modifications needed. European Racing Headers also offers megaphones that bolt on to our headers. These extremely light weight systems are built for big horsepower with a broad torque band. Headers come with all gaskets, nuts, bolts and washers needed. Headers are sold in pairs only. We offer Ceramic Coating Services (See website)!