lucky on the back box there suppose tobe expensive as well, sounds like the exhaust is heavy gauge no wonder they last, on issue i had was the back bow hanging bracket rotted and broke off i had that rewelded and it was heavy lifting it up to temp support it, could of done it myself but I've not welded for years even though I've got one , when i got it back i spayed high temp silver spray paint on it and the back pipes were they are welded.."New" back box was a genuine VAG part I got for peanuts, nine years ago as the back box on the car looked scabby then.
Finally, after waiting nine years, the box has great sheets of rusty steel hanging off it, rattling on the bodywork.
But the internal skin is pristine stainless steel,, still leak free.
I should have just cut off the scabby bits and called it good.
The original pipe will still be there in another twenty years, it took long enough to cut through it.
The original exhaust was stunningly well built.
At least compared to the Renaults, Fords & Datsuns of my youth. 3 years tops.