If the catalytic converter has gone then get it replaced rather than just removing it unless you know a garage that can put a new ECU map on the car to stop the engine throwing up a code from the o2 sensors., if you remove it the car will throw up engine codes from the o2 sensors in the exhaust which are extremely sensitive on those cars, messing around with them or trying to remove them will probably put the car in limp mode and its a pain the sort them out without replacing the sensors, my friend had the same problem with one of these cars and it took us ages to sort the sensors out again without them throwing up error codes. the catalytic converter should last you over 100,000 miles so replacing it once will probably last you the life of the car