I am in the home stretch on a P-51D, being finished as Jasper's Joker, from the Tamiya kit. The thing is, I have found a couple of photos, one showing the plane from the right, apparently with a shrouded exhaust, another shot from the left which shows a pretty clearly un-shrouded exhaust.
Does anyone know if P-51s were ever flown with the shroud on only one side? This seems a bit unlikely to me, but then every time I come across something that seems unlikely, it seems to prove true!
Alternatively, were the shrouds sometimes just removed, perhaps due to damage?
I don't really have a preference in this, although doing one on and one off would add a point of interest to the model, if it's actually accurate.

They could be added later or removed. Unlikely that they would be on one side only but who knows? It's possible.