Exhaust system, checking for leaks

WARNING: This page is about a different car, the 2006 Audi A8, 2005 Audi A8, and 2004 Audi A8. However, it is still accessible from the selected car via links, so may be relevant.

Start engine and let run at idle.
Seal tailpipe, e.g. with cloth or plug, for duration of leak test.
Listen for leaks at the following connections: cylinder head/exhaust manifold, exhaust manifold/turbocharger, turbocharger/catalytic converter etc.
Repair detected leaks.