Branded,
The bolt heads on that muffler are recessed about an inch into the muffler. How would you safety wire them together? I suppose you could use a longer bolt and large washers to keep the head outside of the recess but now you have a lot of the bolt sitting in free space which may cause more problems. I had these same problems until I used the high temp red loctite. The regular red would loosen up after the first engine run. Safety wiring the bolts will save you from losing your bolts and muffler but the bolts will be able to loosen a small amount sometimes even with the wire.