HI KEN ,THAT CERTAINLY POINTS TO A BAD CAT, THE PROBLEM WITH THE AFTERMARKET CATS , THEY DONT GENERALLY HAVE THE SAME AMOUNT OF SUBSTRATE ASSY IN THE CAN AS THE ORIGINAL, AND TWO YEARS IS ABOUT ALL I HAVE SEEN THEM LAST , UNLESS THE LAW ON AFTERMARKET CONV HAS CHANGED RECENTLY , THEY WERE 24 MO 24000 MI, AND THEY WILL GET VERY WEAK OR JUST BE DEAD , DONT BE TOO SHOCKED AFTER YOU PRICE ANOTHER ONE , THE PRICES ON CONVERTORS HAS SKY ROCKED IN RECENT MO,S , HAVE YOU CHECKED THE AIR INJ SYSTEM TO MAKE CERTAIN IT IS RUNNING AIR INTO THE EXHAUSE SYSTEM THRU THE PORTS IN THE HEAD .. JERRY