Start with loose parts rattling around inside a battered cardboard package:
I backed the Forester up to put the rear tires over the edge of the garage apron, which provided enough room to work underneath without jacking the thing; there’s a chock under the left front wheel, never fear.
The instructions from etrailer.com were entirely adequate, so there’s not much point in a detailed writeup. Their time estimate (an hour) seems grossly understated, but I wasn’t in any hurry.
A morning of pleasant wrenching produced a good-looking, albeit nearly invisible, result:
Both hitches bolt directly to the frame and I have no idea what effect that has on the collision behavior. My guess is that the Subaru hitch would be more bendy, if only because it has a much lower load rating, but that probably doesn’t make much difference.
Remove the muffler, which is trivially easy on a new car, and reuse the crushable gasket, which is probably not recommended. After releasing the muffler, you can ease the mounting pins out of their rubber supports without applying any lube or issuing many curses. The tailpipe remains in place, conveniently away from the proceedings.
As others have noted, remove the heat shield, snip a few square inches from the inside front corner, and reinstall with only three screws. I chopped clearance holes for the hitch bolts using a box cutter, but you could probably just punch them right through the butter-soft aluminum sheet.
The instructions suggest drilling / rasping the center mounting holes to 1-1/8 inch diameter. Being that type of guy, I used a step drill to get a 1 inch hole, filed slots on the front and rear sides to accommodate the reinforcing plates, then filed the corners where the slots meet the hole for the carriage bolt heads. The bolts and plates just barely fit, but that leaves more metal on the frame; I doubt any of that matters.
I felt badly about leaving steel filings inside the frame, but there’s no practical way to extract them. I didn’t prime-and-paint the raw edges, either, as they’re buried deep inside the hitch frame; I may regret that decision.
Wear eye protection: those six fish wires have lethally sharp and very whippy ends.
You can support the hitch on your chest to maneuver it into position, but an assistant must hold it in the proper alignment while you fiddle with fish wires, bolts, and nuts.
I don’t know what happens to the raised bump in the frame under the heat shield, but I suspect it gets crushed flat after torquing the nuts on either side.
When you reinstall the muffler, remember to take the gasket off the mounting pin where you put it for safekeeping before maneuvering the pins back into the hangers …
The Official Subaru OEM Hitch Assembly Instructions commence with loosening the taillight housings and then get complicated. That hitch mounts on a crossbar that completely replaces the bumper beam inside the dress cover, the receiver extends through a small square section of the cover that you cut out as part of the process, the mount occupies the two rearmost holes in the frame members, and it doesn’t require trimming the heat shield. It also costs nigh onto $800 including dealer labor.