There are several manufacturers of custom stainless steel exhausts in France, of course some might have a better reputation than others, it's also a route I'm investigating as I need to replace both of my backboxes. The left one has developed a leak around the welding points to the entry pipe, and the internals are rattling. The right one is fine but would need replacing too if I want to have matching sound and looks.
The rest of my pipes are fine even though they have some surface rust but nothing out of the ordinary for an 18-year-old car...