The exhaust was blowing on one of my cars (2003 Golf GT TDI 130), so I took it to my usual (independent) local garage. It had to have a new cat, but now the car does not perform as well and is noticeably slower accelerating.
I'm just wondering why this might be. I know there's various oxygen sensors in the system that could be reading differently, plus the flow of exhaust gas affects the operation of the turbo (although usually it's detrimental when the cat is old and has become blocked, not when a cat is new).
Any ideas? I'm wondering if they may have fitted a cat that is not really suitable for this engine, maybe intended for one of the slower/non-PD TDIs.