I did the same install on my 13 WRX Wagon. Instead of dropping the muffler I was able to get it on by peeling back the rear bumper cover. I only had to trim a small piece of bumper cover on the underside. I use it for my bike rack and hauling a small utility trailer to the dump and back. I did load up the trailer and did a 3 hour drive. It drove great w/o any problems or swaying, even at 80mph.