Exhaust system, checking for leaks

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2004 Audi A6, 2003 Audi S6, 2003 Audi A6, 2002 Audi S6, and 2002 Audi A6. However, it is still accessible from the selected car via links, so may be relevant.

Start engine and run at idle.
Plug tailpipes (with rag or cap) and leave plugged until check is complete.
Listen for noise at connecting points (cylinder head/exhaust manifold, exhaust manifold/front exhaust pipe, etc.) to locate any leaks.
Repair leaks found.