-These headers measure 1 5/8" O.D and 38MM I.D. These Headers are manufactured specifically for the 914.4 motor. Our headers are made in the USA from equal length, mandrel bent 16 gauge mild steel. 914-4 headers maximize flow by utilizing a 4 into 1 Bullet Merge collectors. These headers are designed as a simple bolt on with no modifications needed. European Racing Headers also offers megaphones and muffler type systems that bolt on to our headers. These extremely light weight systems are built for big horsepower with a broad torque band. Headers come complete with Stub pipes for exhaust ports as well as all gaskets, nuts, bolts and washers needed. We offer Ceramic Coating Services (See website)!