Need a replacement catalytic converter for your 2003 Cadillac CTS? MagnaFlow offers high-quality catalytic converters engineered for 2003 Cadillac CTS 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 Cadillac CTS requirements and state vehicle registration to buy the best CTS catalytic converter online that fits your '03 CTS and meets your state’s emissions compliance.