Review on Permatex Muffler Tailpipe Sealer 3 Pack by John Springer

Total bullshit. The quality is in no way inferior to cement, it is brittle and does not stick to metal. It doesn't harden for days, when I started the engine an hour later the gases blew it away like it was a piece of cheese. Does not withstand loads and vibrations, cracks after a few hours. If you have a dime-sized hole in your muffler, it will likely clog it for a while, but nothing more serious. It is not clear where these positive reviews come from. Don't fall for them or you will suffer the consequences.