If you're looking into as strong an adhesive as you can find, odds are J-B Weld will pop up during your search. J-B Weld is recommended for use on wood, metal, concrete, and more, with the brand recommending it for tasks like light automotive crack and hole patching, carpentry, and plumbing repair. It's explicitly stated on J-B Weld products that it's not intended for flexible or structural applications. That means if your muffler completely falls off, for example, you can't just J-B Weld it back on and drive around without it cracking and falling off again. At this point, there's more to the J-B Weld name than the original adhesive that started it all.