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2004 Ford Mustang Deluxe 2dr Coupe

2004 Ford Mustang
Trim Info:
Rear Wheel Drive, 2 Door Coupe, Subcompact
20 mpg city / 29 mpg hwy
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September 23, 2013, 6:13 pm

John B

Question: Can aftermarket exhaust headers wear out catalytic converters?

I recently purchased a 2011 Ford Mustang GT. The previous owner had installed a complete aftermarket exhaust system, headers, cats, and pipes. However the catalytic converters are now bad. I took the car to a mechanic and he confirmed that the converters are bad and he said that everything including the headers needs to be replaced with factory parts. He said that the headers are not bad but that they are causing the catalytic converters to wear out. Could this be true? If I just replaced the converters with aftermarket ones would I have to worry about the headers wearing them out?

October 6, 2013, 10:19 am

Richard W
Expert Mechanic

The person that had it before you replaced the cats when he did the other exhaust work. When he did that he could have got bad weak cats. Also a header will not cause a cat to go bad. Hitting the throttle and driving the car hard will cause a cat to go bad.

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