I concur. First tighten down all the header or exhaust manifold bolts and collector bolts. I had a similar sound pop up on my car on a long drive and my fellow mopar friends and I thought it was a lifter. As it turned out, 2 header bolts had loosened a few turns. Tightened them back up and the sound was gone! When I got home I installed header bolt lock clips.Absolutely sure it's not an exhaust leak...















