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Hoping for a little help on buzz/rattling exhaust

Discussion in '2015+ S550 Mustang Talk' started by Atticaz, Nov 9, 2018.

  1. Atticaz

    Atticaz New Member

    Nov 9, 2018
    Surprise, AZ
    I’m curious if this is a sign of a cat going bad. I have been smelling a slightly stronger oder from the exhaust... not a rotten egg smell. There are engine codes showing. But I have also been getting knock retard as high as +5 in part throttle and at wide open throttle, both on stock spark tune and MPT PRX91 tune.

    Any help would be great. Thanks. See YouTube vid.


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