There isn't much off-roading support for the X3 or any BMW for that matter since they're not really designed to be Jeeps. I've taken mine on an ATV trail and various farm and gravel roads but that's really about it. The ground clearance and lack of locking diffs are going to hinder serious off-road performance. There's also limited suspension travel and the relatively low-profile tires. The X3 was really designed to go around corners at blistering speeds like a sports car.........on road.

That said, do as you wish. Not sure of off-road aftermarket stuff.