Cat. replacement 1.9(93)

Gettin' the puffin' from around the heat shield area..I am GUESSING the cat.(seam).I haven't looked close or done one of these on an Escort.Should I be prepared and have another heat shield,exhaust manifold for when I find the studs toast?Can these be run without the heat or cat. heat shield? Can one of these cat.'s be fixed for a while with muffler cement or epoxy?..Thanks a lot..Arnold..