I don't need very much arcane knowledge to know that holes in the bottom of your exhaust are A Bad Thing. So I spent all of yesterday replacing this. How hard can it be? Two clamps on the horny bits, and one more to join the stumpy pipe to the swan neck that leads down to the exhaust pipe under the car.
Hahahahahaha. It took me 6 hours, 4 cups of coffee, some weeping, several calls for moral support and All of My Fingernails. The first problem is that the horns are very much wider than the hole in the bottom of the chassis that you have to get them through. So there is a lot of wiggling to drop the old one out of the bottom of the car, and then you have to try and remember what you wiggled in reverse to get the new one in.
Then you have to hang the hooks off two bolts sticking out either side of the gearbox. In theory this should be easy. In real life you can only see one side of the gearbox at a time, and when you've got them more-or-less lined up there's a brake duct stopping you from dropping the box down onto the hooks. The presence of a Handy Helper would have made this part much easier, but sadly next door's children are still too small for any practical exploitation. The instructions stress the importance of having a washer between the exhaust hook and the gearbox. This has only been possible on the side which I could see. I hope it's desirable rather than essential.
Then you have to clamp the horns to the Heat Exchangers. In my fantasy world of Straightforward Exhaust Fitting they would line up and it would be easy. But they don't, unless you loosen the front of the heat exchangers for more wiggle room. Two more clamps to undo, scrub with wire wool and WD40, cover with exhaust goo and do back up, while holding the two pipes as close together as you can manage with one hand, while the other hand tries to get the clamp on without dropping the nuts or the bolt, because now it's getting dark and once they're dropped they're gone.
And when you get all of those as close as possible and not leaking too much there's a half-inch gap between the short horn and the swan neck.
At about half past one, in my second hour of not being able to hang the new box onto the bolts, I stopped for a cup of coffee and a small cry. Does that ever happen to blokes in Kwik Fit?