The APR Audi B6 S4 V8 exhaust offers the best bang for the buck!
APR CB100017 2.25" Stainless Steel Cat-back Exhaust for Audi B6 S4 Sedan, Avant and Cabriolet
APR's B6 S4 Exhaust is offered as both a full or as a catback system. The catback system is a complete stainless steel, mandrel bent, cat-back exhaust. The APR B6 S4 exhaust is a dual 2.25" system that begins at the factory Audi B6 S4 downpipes and continues to an innovative center muffler. The APR exhaust then splits and each mandrel bent pipe goes to its own muffler with a 3.5" (90mm) bevel-cut, round tip.
The APR CB100017 B6 S4 catback exhaust is very quiet and simply changes the tone of the S4 V8s exhaust to a deep, unobtrusive sound. With TIG welding, fully stainless construction, and CNC'ed hangers, you will not find a higher quality system on the market.