I agree with Terminator 100%. I purchased the OEM hitch and wiring harness ($450 in 2006) for my '02 X5 and did the installation myself following instructions and photos available online. The entire job took about five hours at a comfortable pace, and less than a six-pack for anxiety relief when I thought about removing the bumper cover. The OEM hitch bolts up perfectly to the frame rails and includes substantial reinforcement to make up for the normal bumper shock absorbing components that get removed. In addition, having the OEM wiring harness is the only thing I would ever consider using given the sophistication (over-engineering) of the X5's electrical system. As it is, the LED taillights on my trailer confuse the body computer because it expects to see a higher amperage draw when they are on. So at times, it thinks the trailer lights are burned out and will put the turn signals into "rapid flash" mode.

Stick with factory on this and you'll feel a lot more comfortable no matter what you tow.

2002 X5 3.0 237,000 miles
2004 325i 106,000 miles