I just had a $600.+ repair on my 2001 Subaru Outback Wagon (4 cyl.) Two days later we were pulling a small utility trailer and the trailer popped off the ball on the hitch, and slid under the Subaru puncturing the muffler. The price to replace the muffler at our dealer is $400.00. Ouch! Is it wise and can a muffler be repaired? My understanding is a Subara muffler is meant to last so other than this puncture, it’s working fine. The puncture is about 1/2 to 1 inch in size.
You don’t need to stick with the Subaru muffler. It is likely a good one, but there are good after market mufflers as well. It’s your choice.
Without seeing or hearing the muffler, it is difficult to suggest if you need a replacement or not.
There’s also the question of whether the OP needs to deal with a state inspection.
But I agree, and aftermarket muffler is fine, as long as it’s a “direct fit”. Some of the “Rube Goldberg” contrivances out there are scary!