For Audi TT Quattro Mk1 1.8T Stainless Steel Turbo Downpipe/Dump Pipe Made of high quality T-304 stainless steel with computerized mandrel-bends TIG welded CNC machine flange for strength and durability Increase engine output and efficiency. Gain 10 - 15 HPs (approximately) O2 sensor bungs insertion, bolt(s) and metal gasket(s) included Inlet: 3" / Outlet: 2.5" / Piping diameter: 3" with welded flex pipe