Custom ATP stainless steel 3" downpipe designed to work with Longitudinally mounted 1.8T cars such as Audi A4 and VW Passat. Made to work with ATP cast iron manifold and any of the following turbine housings: GT28RS 5 bolt, GT 4 Bolt 3" opening, GT/T3T4 - 4 Bolt 2.5" opening, T3/T4 External wastegate 5 Bolt, T3/T4 Internal Wastegate 3 bolt, . 3" diameter stainless steelAND the appropriate V-band adapter to the particular turbo (V-band clamp included). has provisions for the factory oxygen sensors.