Where is the hole in the muffler? Is it in an easy to access place? If you can get to it easily, have it welded. For the few bucks it will cost, it will be worth it (cost $20 for me). I used JB weld for such a repair (on my center muffler), but only for an emergency. I had it welded 2 days later, so I do not know the longevity of JB Weld.