The rubbing of the bumper to the fender flares has to do with the alignment of the bumper onto the mounting bracket (to some extent). ARB recommends a certain spacing between the bumper and the FJ (can't remember the exact specs at the moment) both horizontally and vertically which one can adjust prior to drilling the locking hole and installing the locking bolt.. You probably have the bumper installed too close to the FJ and some adjustment may need to be done if you are not happy with the gouging.
to realign the bumper you would have to remove the locking bolt and loosen all the bolts from the bumper to the mounting bracket. Move the bumper up or down (using jack) or out or side to side, then redrill the locking hole and tighten all the bolts
I haven't noticed any rubbing on my install.
Here's a pict of the spacing I have on the passenger side.
T