Ah, the Mopar heat riser! My first issue with one was the day I bought a 70 Challenger, just a 318 Vert back ion late 80s. Ran good, of course it was for sale, and back then a guy would be there to look 24 hours after I got it home. So I fire it up, exhaust was a little loud, it had been sitting in a cow pasture a while. He hears this tic tic tic and gets in hos car and is gone, just like that. Bout then, I figure it is the darn heat riser flapping. Ever since, I extract the darn thing, and weld the holes shut!