I remember after driving around with the stock muffler, and then turning the car off, the muffler would make "Ticking" Sounds...

But once i changed to a free flow muffler, the Ticking sounds went away.

Is it just the way the factory muffler is designed, or is the stock muffler that Hot and restrictive?

 

From what I have heard over the years, dissapating heat is the cause. Basically, the muffler cooling.