Does anyone know how to replace the OS before cat? or perhaps how difficult could be? I checked underneath and looks difficult based on space to work but from top looks a liitle bit easier too reach but what it looks challenging would be running the conectors. I have checked on prices and I've made my decision to buy a new one with the conectors and not the ones I would need to splice and reuse the old conectors. I had some people say not to use the Universal conectors and use the OEM otherwise most likely I would have the check engine light showing up again. My TT is 2000 Q, perhaps someone has the Part# too, I've called the dealer and they asked about how many cables and what part number it is and they could check it for $70? another rip off.