I have been able to fix one muffler with alumiweld, but not another. There is a definite technique to learn to use it. You can make a large area of damage trying to make it work in this case due to the nature of the base material and the heat required to make this work. The second muffler I just had to flat out replace. Alumiweld works more like a solder, and you need to "rub" the stick to make the metal stick correctly. It does work, but TIG would be better.