My exhaust sounds like a Harley w/ straight pipes upon decceleration. (Well, not that loud), but there is a definite "rasp" about its tone when the RPM's are descending and an occasional "popcorn" noise that I don't particularly like. The Cat has 130K on it, however the car has been well maintained for all of tose original miles. The cat-back exhaust is 4 months old. Is it time for a new Cat?