Audi Header Pipe | A4 Quattro - 2001 2000 1999 1997 The Audi Header Pipe improves efficiency by reducing resistance to the expulsion of exhaust. For adequate motor function, exhaust fumes must be collected from every cylinder and extracted by means of exhaust system pipes using your Audi Header Pipe. The Audi Header Pipe is essential for the most efficient operation of your engine.5/5(2) 2000 Audi A4 Exhaust Pipe - AutoZone Equip cars, trucks & SUVs with 2000 Audi A4 Exhaust Pipe from AutoZone. Get Yours Today! We have the best products at the right price.