We've got a '02 (mk6) 1.4 zetec and last week, all of a sudden, the standard exhaust started burbling and popping on the over-run! I thought it was the back box, as it was still the original Ford 1 piece exhaust. Went and got a new exhaust, as it was only £65! Fitted it up no problems, no leaks but, still the same if not worse!? Could it be the cat gone? What do you good people think?!