Yes. The Audi 2.7T twin turbo and 2.8 NA V6 are interference engines. The later generation V8 is also, but I believe they have chains. The recommended interval for changing the timing belt should NOT be ignored. If the belt breaks or slips you will have valve damage and more than likely piston damage as a result. At the time of a timing belt service, be sure to replace the water pump, and TB tensioner as well as the belt. All of these things can be accessed or are easily accessed when doing the belt.
The 2001 Audi S4 has a V6 engine.
The 2001 Audi S4 has a 2.7 L base engine size.
The 2001 Audi S4's engine produces 250 hp @ 5800 rpm.
The 2001 Audi S4's engine produces 258 ft-lbs. @ 1850 rpm.
The 2001 Audi S4 has 30 valves.
The 2001 Audi S4 is a gas-powered vehicle.
The 2008 Audi S4 has a V8 engine.
The 2010 Audi S4 has a V6 engine.
The 2006 Audi S4 has a V8 engine.
The 2011 Audi S4 has a V6 engine.
The 2002 Audi S4 has a V6 engine.
The 2013 Audi S4 has a V6 engine.