This is a test of commonsense. Complete the next sentence:

How to install a subaru outback trailer hitch 
Purchase the appropriate after-market trailer hitch kit for your model year subaru outback. 
Inspect the parts for damage and to ensure that they are all in the kit. 
Raise the rear of the outback and place it on car jacks.
You could do your work while the outback has all 4 wheels on the ground, but it is much easier to raise the rear end. Remove the 4 hangers , 2 per side, supporting the exhaust pipe.