I have noticed that the edges of the various muffler brackets are sharp and unfinished. In an environment with lots of vibration and heat, cracks can start at sharp edges and burred edges. The cracks then propagate through the part from cyclic fatigue. I have seen similar cracked brackets on other cars. This is always a concern with high-performance jet aircraft as well. The bracket can be welded by any muffler shop, or any other shop with normal welding equipment. It may be a good idea to take it off for welding. The high current of resistance welding could damage the alternator or other electronic components. I would recommend smoothing off all edges of any sheet metal parts that are removed from the car for any reason. It's always a good policy, and makes the cars look better, and safer to work on with bare hands.