I've got a 2014 300 with the Pentastar motor, & it is noisy on cold start & for about 2 miles, but then it quiets down.
That sounds like my '13 300S, 85,000 miles. Kinda sounded like exhaust leak. Took it in and they found 5 bad rocker arms, they replaced all 24 with an updated part, all under warranty. I had them change the plugs and PCV since they were already in there and saved a few bucks on the maintenance. I traded it off shortly afterwards not because of any engine concern but found a smoking deal on the '16 300 I have now.
Robert
