the point being that since your npcs level up when you, if they hadn't done it that way your npcs would have been frozen at whatever level they were at when you hit 50. so that's nice...
several people made exp. cap removers for the game. you load them like you would any other mod. i never used one so i don't know where to get one, but terra-arcanum would be a good place to start. i've heard mixed reviews about how the affect the game - i.e. the game is built/balanced for a level 50 cap, so if you take it off it gets really easy.
