1 5/8" outside diameter 38mm inside diameter for Porsche 911. The same design as used on the 73 & 74 RSR cars. These are well made headers that will increase performance and last a long time. We have tried the headers available for less and they quickly fell apart. Includes street adapters for use with factory two in two out muffler (see our OEM parts catalog). Header kits include all needed gaskets, nuts, bolts and washers.
