I doubt it was the cv shaft in the first place. Cv shaft noise will be all the time not only when you back out and goes away after a bit of driving.
I would check your brake pads, rotors, and caliper for proper function. Then check the dust cover for corrosion build up and touching the disc.
As for the torque value for the cv shaft it is 305 ft lb.

__________________
2004 X5 3.0