Materials used in new cats are cheaper (nor precious metal) and therefore cheaper, if you buy one a I did look for a guarantee, mine came with 2 years so I can can change it every 2 years for almost 8 years without loss but I'm sure that won't be the case, by the way the one I bought are also badged as MG Rover oem by the like of Rimmers at a premium, and by the way you can buy replacement flanges to weld on if you are so inclined but if you existing is salvageable and able to be welded it could eventually collapse inside and become worthless.