Took my 2017 charger hellcat into the Dodge dealership for a recall on O2 sensor. So they replaced both cats and sensors got my car back and sounds like the exhaust is muffled and not running right took it back to them with the same check engine light on and they said the sound could be the new cats puts on! (Catalytic) Answers please!!!!!
Update tune accompanies cat replacement. It moves the cat overtemp protection to favor the cats more and make them last longer. Also tends to force rich condition to flush cats to cool them down when the temp threshold is reached.