"I don’t like to replace parts before it is necessary,"

And neither do I. The problem is that necessity often pops in for a visit at the most inconvenient times. Only you can judge if the piece of mind of a new exhaust system is worth the price of admission.

If it's a car which will be used for out of town trips or must be counted on for daily service, I would renew the system from stem to stern before the snow and slush are ass deep.

Rich Near Pittsburgh