How much do you think it would cost for my new 20" rims to be installed? Should I have them installed at Ford, or at a mechanic?
Why don't you just go to local shops to see which is the cheapest? Honestly, I wouldn't go to Ford...my dad and brother went to a local shop and got it done.
Installed as in put on the car? Why not do it yourself as long as you have everything. Go and buy a good torque wrench for far less than what it would cost to job it and take care of it yourself.