Hi Jim
Don't know if this will help but worth having a read through, i know some of the earlier Xf Jags have the same engine as the FL2, 2.2 diesel some of them came with swirl flaps, then i think after 2012 without swirls.
These swirls can break off in the manifold and damage the engine, so it's best to remove the manifold and fit a later one, or take out the swirl flaps of the manifold on the car you have, i don't know if the 2.7 - 3.0 XF have them ? good hunting.
https://en.wikipedia.org/wiki/Jaguar_XF_(X250)