I think it all depends on the laws of the countries where you install these upgrades and improvements. For example, in Europe, you can't install the exhaust system so that the rear exhaust goes sideways to the top, as they do on American and Australian trucks. Somewhere there are restrictions on additional light sources that shine at 200 meters or 218 yards if you
convert to the American system. The question of improvements is very subjective and limited by country or regional requirement.