A few more pics would be nice to help get a feel for the location. If it were mine, I might think about simply tig welding on a new tab, but maybe make it a tad thicker and wider (coped out to provide a wider amount of contact with the tube). You might also think about welding on a wall doubler first out of something a tad thicker than the .035 wall tubing to create a "pad" to weld the bracket to. You can buy a small piece of 321 sheet to make the bracket or you might "cheat" and use some 304 stainless (I have scraps laying around so I would use 321).
That pipe looks pretty solid it will tig weld just fine with stainless rod.... once the pipes get much older and corroded, they can get to a point that weld repairs become less suitable. Weld repairs to non heat treated aircraft parts are not uncommon, so long as you use sound aircraft welding techniques.
I would refrain from using auto muffler straps or changing the basic design..... The feds don't go for that kind of stuff (often for good reason).
I just made some pipes for my cafe racer using some surplus 321 tubing I picked up at Oshkosh. I love the stuff, but it is stupid expensive (+$20 per foot last time I priced some new 321 from an aircraft supplier). In thin walled light weight exhaust systems, it holds up better than 304 in extreme temp use with corrosive exhaust gases and can be used in the "as welded" condition.
