Hi Can i throw in my experience, such as its worth. My day car had a new cat fitted. Driving the car home felt as though someone had change the engine to a sports model. The car appeared to be much more responsive, sounded sporty when faster? with a lot of feed back and vibration through steering wheel, gear stick. After a few days i became tired of the noise and vibrations, took the car back to find that the cat was touching the heat shield, my old car was back!