Complicated subject, Simon. In the black cover Factory Illustrated Parts & Accessories Manual for '85; on pg 33, there are 5 (five) different ANSA exhaust systems shown for Panteras. Series one thru four plus a 5th for GTS & GT-5. There's also a 'big bore' system (#6- no illustration) for the Gr-3 street-legal- racers, with or without internal baffles. Might be too loud for the street, or not?
Some part numbers have tipped up tailpipes, some tips are straight-out, some use flat gaskets and some use doughnut-style gaskets. There are matching headers for them all, which changes the overall length. Matching up two loose mufflers via the Web for exact Concours is a nightmare. Most don't bother.
Your TUV guys will have lots of fun sorting things out if you have a copy of the Manual..As usual, the whole 90 pg Illustrated Manual (9' x l4") is available on the POCA Web Site for member download. On top of all that, the ANSA Exhaust Company was sold twice and what they're making now under that name is not exactly what they sold 40 years ago. Good luck-