Wilder, you need to explain more about NYC for MM2. It's ok to leave not many .ar files in the own game folder, but this city needs other things to work.
For first, New York City for MM2 isn't a mod by an add-on city for the game. To play this city you need to configure the graphic options and you must play it with certain cars and traffic/pedestrians/cop densities; check what's written in
this topic. This is for both the original and the improved version.
There are some topics about this, you could do a search before.