[Rare Iron]

The only way these Cobra mufflers would "rattle" is if the cores come loose inside, then it's simply time to replace them with something else. High horsepower does not make them rattle - something wrong with the construction does, or if they are old & the cores get rusted-out. Old mufflers can look good on the outside, but when you cut them open they can be rust flakes. Cut many open at Tenneco & many that were just 2 years old were rust powder inside.