Need a replacement catalytic converter for your 1990 BMW M3? MagnaFlow offers high-quality catalytic converters engineered for 1990 BMW M3 sub-models and engine sizes. We combine efficient design and state-of-the-art manufacturing to meet or exceed required emissions standards. Select your 1990 BMW M3 requirements and state vehicle registration to buy the best M3 catalytic converter online that fits your '90 M3 and meets your state’s emissions compliance.