Open the trk in a def file after using N3def and scroll down to the walls section. the first line will be the outside wall, the last line will be the inside wall. Any other lines in between will probably be pit walls. the first number indicates type, I have yet to see a difference. The next 2 deterine the distance from the center of the track and the last 2 are meaningless. Make a wall distance smaller or more negative to move it out and bigger/ less negative to move it in. Then open up the 3do and move the points around to match p to the wall. The units are the same from trk to 3do but the corners in the 3do can be painstaking.