I only used that 206GTi diagram to show that the centre pipe is available seperately from the Cat...
Note:
1: ALL CC's have two lambda sensors fitted..
2: The 206 3 or 5 Door centre pipes will NOT fit any of the CC's..
3: The Back Box on the 1.6CC is the same one as fitted to the 206XSi..
4: The Back box on the 2.0CC is the same as the 206GTi..
So you need to get the correct part numbers for the aftermarket centre section.. Most exhaust places should be able to get that info from the likes of Arvin Merator (Timax) or Bosal etc
I will also say that the Peugeot Exhaust material is Very Very Good as it is made from comparatively thick wall steel tubing. Compared to the aftermarket stuff that is thin and nasty.. It is unfortunately only that rear flange that is a weak point as the condensation sits on top of it and rots it from inside out.. Its a common failure on the 106/206/306/Saxo etc
Mine did it a month or so back. And that was after 60,000 miles.

So I had a small stainless piece made that sits between the centre box and back box.. Cost me £60 total..
Carl: There is Only 1 Cat