If it is coming out of the cat you will have a loud unmuffled noise with the leak.. Unless you do have the noise it ain't coming out of the cat.. What you have is something on the cat that is melting or burning or a leak that is blowing liquid on the outside of the cat.
I have seen MUD on a cat smoke from the heat. Also leaves or other trash will smoke..
Bif Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist