Originally Posted by waja
The bolts and plates need to be installed with the bolt heads and plates inside the the frame channel. There are two recommended ways to get the bolts into the channel. One is to enlarge the existing holes, the other is to remove the bumper which will expose the open end of the frame channel and provide access points that are large enough to allow the bolts to be placed inside. You can see the rear bolt heads in this picture.
And that was an excellent explanation. I really don't like the idea of drilling ANYTHING on my newer Subi. I guess bumperless install is the way to go.