Originally Posted by Lemans_Blue_M
OE exhaust applications typically go overboard on such things like heat shielding to avoid unintended consequences. (even if the chances of any real impact are remote)
The engineering group at Arvin Meritor, (M3 OE exhaust supplier) probably suggested this to BMW during their R&D.
This precaution was implemented due to the close proximity of the dual exhaust pipes as they 'snake' around the differential casing
I can't see that it would make much difference, but I guess it wouldn't hurt to re-use them. (or fabricate something similar)
I would only do this if you are truly concerned about the additional heat transfer from your unshielded aftermarket exhaust.
No idea how much difference it really makes...
I think the diff. would withstand heat better than the rubber parts of the CV like Ilia@IND suggested. Worth looking into IMO.