exhaust leak sealant?

I have a leak between the cat and the exhaust piping heading towards the back of the car. I bought some muffler cement from crappy tire and sealed the area with 5 layers of it, but after some driving the seal breaks and air leaks out. I have a gasket installed aswell. Is there a better product out there thats meant for this and is water proof?

Yeah I’ve never had much luck with that stuff either. Is it the kind that “bakes on” after driving? I just don’t think it stays flexible enough along exhaust joints and winds up cracking.

How about buying a new gasket?