Need a replacement catalytic converter for your 1991 Buick Regal? MagnaFlow offers high-quality catalytic converters engineered for 1991 Buick Regal sub-models and engine sizes. We combine efficient design and state-of-the-art manufacturing to meet or exceed required emissions standards. Select your 1991 Buick Regal requirements and state vehicle registration to buy the best Regal catalytic converter online that fits your '91 Regal and meets your state’s emissions compliance.