I might be able to help, I have an exhaust that the clamp end is knackered, so you would have to re weld that, but the rest of the pipe is good and I could cut it off and send to you.
The section of pipe that fits between the header pipe and the exhaust "box" sits behind the RH side panel. It is horizontal so hols mud. If the TTR gets put away wet then eventually it rusts through at that point.
I did consider at one point making up a repair section to allow owners to cut off the damaged pipe and weld in new but it was uneconomical. Better to buy one of Steve's lovely new stainless jobbies