I actually have that kit that I was going to install on a our VW Routan back in the day. I
I noticed the other day while cleaning up the garage the box is still sitting there. I have been kicking around the idea of adding them to the X5 since we basically bought the SUV to tow.
Our little camper (1500 lbs) probably isn't heavy enough to justify them but we may get something bigger. Unfortunately when I put the little camper behind the X5 its going to lose its status as the fastest popup camper in California.