I had some holes in my pipe and the auto parts store guy had a cool idea. I am sure many of you have heard of it before, but its still a good idea. What he suggested is that I take a tube of exhaust sealant (I guess the stuff you put on joints to seal it) and a tin soup can. You cut out the ends of the soup can and slit it up the side, then goop up the inner surface of the can with the sealer and then wrap the can tightly around the pipe and clamp it with exhaust clamps or hose clamps.