The doors on my 01 4.4i are heavier and more quality than my Range Rover Sport. I too hate it so much when my kids slam them. The lighter doors on the RRS seem to catch air resistance and it's no big deal when they are slammed. Apply the same amount of pressure to the X, and WHAM!!!! I bet that's why the window regulators suck so bad. The doors shut too hard!

Anyone think of adding some weather stripping to take away some of the force? I don't know where one would apply the said stripping, but It'd probably do the trick (and save the window regs)