I believe there's engine mods available from Startech or others and since the they have $$$$$$$to build them have at it .Just remember your working on a $7k-10k driveline and if it's still under warrenty it won't be after your mods in your garage ! If you think my warnings are stupid then have at it.The ECU upgrade and airintakes are available and do add about 30HP cost less than $1k.These don't harm the warrenty so far.
My idea of having a fast modern car is buy it with all you want.Don't try to mickey a great car. As for the XF being a loss I think you're wrong it's one of the best values I've owned .I've had a year and still get compliments almost every day I drive it.

Good luck .
That's why they make Hondas.