Exhaust Leak On T100

I have an exhaust leak and need your help in sealing. I believe it's the cause of the popping while decelerating. I blew air into one end of the pipe and sealed the other while I sprayed soapy water on all the connections and found bubbling. The leak is where the pipes meet underneath and are held together with a coupling. Should I hammer them back with a mallet? Should I use this red high temperature seal on the outside or should I remove them and place it on the inside of the pipe?

 

It does, I removed the clamp to inspect it.