Batman, My KLR had approximately 46k miles on it when the cat started to break up and clog the pipes. The engine was replaced with a 8k mile 1998 engine right before I bought it but he left all of the original attachments on like carb, muffler, starter, etc. Thing is I could have cleared the pieces and welded it back up. My guess is that this could happen anytime it lands real hard on the cat or it becomes submerged in water while hot. These are lessons I learned while piloting my submarine, um I mean Jeep Wrangler.