Thanks for the bad news Nev , I'm in the same situation, been bodging for 7 years , now not much but rust left, had a look underneath just before the MOT and had to cut off all the U clamps cus they were just rattling about and not needed cus it's so badly rusted up.
I've got an idea I might buy the standard system and cut it up to repair the one I have, mine doesn't look too bad after the middle silencer.
I've had similar issues with the water pump and also stuck radweld in just before Xmas , it's not needed any water since