These headers measure 1 3/4 inches O.D and 42MM I.D. and are recommended for 3.4 - 3.8 liter Motors. 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 and stinger systems 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. Ask us about Ceramic Coating Services!