Good luck - and be sure to post pictures and keep us all up to date with your progress.
So far, many have talked the good talk - but no one has yet to walk the walk. Much less post pictures and tell their story. I have yet to see a stock XF that has turbo'ed, supercharged, NOX, etc. Not saying it can't be done, or hasn't been done - just that no one has posted anything to this forum that I know of. I'll keep an eye out for your progress.
Sure - you could drop another motor in - but most people don't buy new cars to do a motor swap. Startech offers a 6.1 V8 rated at 426 HP motor swap. But that seemed like a ton of money and long lay-up time for only +30 HP gain.
http://www.startech.de/p13e.htm
I wish you luck, you seem like a good mechanic with lots of tools, time and money.