Honestly, none of the aerodynamic upgrades will provide any performance benefit for USA drivers. We do not have an autobahn here and we really won't benefit from improved aerodynamics on our cars. We just don't get up to those speeds.
In Europe, its very common to see complete "Autobahn" packages of mods tailored for high-speed driving where you have high-engine speeds. Exhausts, brakes, tunes, wheels, lighting mods and aerodynamic alterations can be selected in such a way that they give maximum performance for autobahn driving.
Here, its more of a visual thing. Call it "Optical Tuning" if you want!
