I have what I can best describe as a churning noise coming from my 2014 Charger Police with 5.7, with only 3800 miles. Car runs great, no engine lights, and I cannot hear the sound from inside car when driving, only when idling. Mechanic used his stethoscope and could hear it in the intake area. We then felt the PCV hoses (I have a BT catch can) and you can feel it in one of the hoses. It's not a steady thing, like I wrote, it's kind of a cyclical churning, almost a grinding but not that rough. I wish I were better at posting video.
Car is well maintained, everything looks normal under hood, no kinked PVC hoses, and definitely does not sound anything like one of the common issues with the 5.7's, e.g., lifter tick.