One problem related to manifold/header/muffler/tail pipe has been reported for the 2001 Audi A6. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Audi A6 based on all problems reported for the 2001 A6.
Audi's 2. 8l v6 engine, from the late 1990's forward to current v6 engines has this problem. The cam adjusters commonly leak oil, and these leaks drip oil onto the exhaust manifold, which presents a fire hazard.