There is only one on the half system, the other CAT being in the OEM silencer box - do you mean you have misplaced the front cylinder pipe - it would be hard to loose as it's huge
Yes, annoyingly I have done just that. For misplaced read; may have accidentally slung it when clearing out the barn! Although it may be at my garages up the road but I don’t recall seeing it there so I would still grab another just in case.