This K03 turbo flange is used in our Audi B5 A4 1.8T High-Flow Cat and Test Pipe. It is CNC waterjet cut from 3/8" thick 1018 cold roll steel or 304 stainless steel. The center hole is counterbored to accept 3" piping.
This flange is available for those building a custom downpipe or test pipe. Gaskets and hardware are available separately.
OEM Longitudinal K03 Turbo Gasket | OEM VW Turbo-Downpipe Lock Nuts