As promised, here is a tutorial on modifying the misc01_start_p30.pac file to enable you set a different arena for the Royal Rumble match. First its important I state the restrictions set by the developers for the Royal Rumble and Elimination Chamber matches. 1. In Exhibition mode, The 10 man, 20 man and 30 man Royal Rumble matches  are always played in the Royal Rumble arena. This can't be changed in the game's menu 2. Elimination Chamber matches are always played in the eliminat