Need a replacement catalytic converter for your 2003 Audi S6? MagnaFlow offers high-quality catalytic converters engineered for 2003 Audi S6 sub-models and engine sizes. We combine efficient design and state-of-the-art manufacturing to meet or exceed required emissions standards. Select your 2003 Audi S6 requirements and state vehicle registration to buy the best S6 catalytic converter online that fits your '03 S6 and meets your state’s emissions compliance.