At the end of the day its the water that rots from inside out. Dont know if shorter journeys speed up the rotting, as not getting up to temperature.
Winter weather gritting salt also has a bearing on life also. Do you live in speed bump heaven or hell, all these things dont help.
At the end of the day if it lasts 7 years or more is not that bad really. We expect things to last for ever, then moan when they break.
In the year of cortina excort etc if they lasted 2 years that was it. But somebody above hit the nail on the head,why not have a patent exhaust??
I have bought wheel centres and a few odds and bods lately from the far east. Brand new for pennys and then been informed the item is no
longer available. I have recieved them all but the listings have gone.
All i would say find somebody to make you one up in mild or stainless steel. And yes it can be as quiet as stock i have had them myself.