Not sure how much a winch would weigh, but I believe the shipping weight on the bumper was somewhere north of 100 (maybe even 150) pounds. Add that to the Kilby skid plates and eventually the winch and I bet you do get close to 400 pounds or maybe even a little over.

Besides the obvious aesthetic upgrade, this is the primary reason I'm considering a big brake kit when the rotors/pads need replacement.