The auto shop I took it to; he got the ford parts to install on it. Nothing else is upgraded from the manufacturer that I know of. I've read on the forums of people getting self-leveling shocks though. They will run you about $800 for 4 + installation. I've also read about people installing Light Truck tires because they are rated to up to 80 psi and can handle a lot more weight than passenger tires (the stock tires). The tires will cost around $140-$230 a tire.
The only other thing you can check is the gear ratio I think it is 3.73 standard on this vehicle though.
check this page to see what your gear ratio is.
http://www.drivetrain.com/parts_catalog/ring_and_pinions/what_rear_end_ratio_do_i_have_in_my_ford__is_it_posi.html
