Got a 2015 XFR. Good car but not a smooth as my previous X350. Noticed a slight engine rattle on initial start up. Goes away after 2minutes and doesn't reappear unless left overnight. Dealer says all S/C engines have it and is from the mechanical fuel pumps. Any body had similar experience
Auto fire

 

Sounds like it maybe Catalytic converters heating up...Normal

 

Direct injection.

 

Thought about catalytic converters after your suggestion. The noise is gone suddenly after about 2 minutes. There are two converters and I would think that one would be up to temperature in advance of the other. The noise goes completely suddenly.
Auto fire NZ.