I felt like going back to this track today, so I did. Here's what I did.
-added some infield banking
-added some more trees
-redid some aspects of the pit stop to get it closer to the source material, such as adding walls that go back to the garage, and making the pit wall invisible
-moved some walls forward and back (turn 4 and turn 8)
-added textures on wall ends that were missing them
-started adding custom textures to the walls
-added some billboards to the downhill slope leading to the underpass as well as changed the wall on the right side to a short and wide one like the game
-removed a nasty piece of code from track.ini that instantly disqualified you if you attempted to qualify
-extended the grass in some areas, and removed grass on the overpass bridge
-attempted to smooth out a bump on turn 5
There's still much more I'd like to do like add custom textures to all walls of the sponsors on them from the game, add at least a placeholder for the bridges that go over parts of the track, make it sunset and add lights to the track, and in general add as much detail as I possibly can.
