I've heard mixed things about remapping a 6 speed xf because of the autobox being on its limit in stock form, however i got to thinking and realised that the bmw 335d uses the same box and people take those upto ridiculous levels of power and torque so it should be alright, shouldn't it?
So what are your opinions?

 

The XFS puts out 600 Nm of torque and the 6 speed ZF 6HP26 it came with pre-2012 is rated for max torque of the same amount.
I put a tuning box (Racechip Pro 2) on my old 2010 XFS which took it to 700 Nm and I had zero problems.
The later/current X260 XFS diesel is rated at 700 nm and uses the later 8 speed ZF 8HP70 which surprise surprise is also rated for max torque of 700 Nm (that is what the 70 signifies).
BUT, those max torque rating from ZF are extremely conservative and there is little question both the 6 speed and 8 speed boxes can safely handle a fair bit more.
Many F-Type R owners (same 8 speed ZF box) here have tuned their cars to well over 700 Nm and I have never read of a single instance of gearbox problems.
However that may be mainly or even entirely due to the way the Transmission Control Module (TCM) interacts with the Powertrain Control Module (PCM) to limit torque.
Apparently if and when the TCM detects "excess" torque it tells the PCM to back off a bit and reduce the supply of power/torque.
Bottom line - just go for it!