Yep! Another game I'm hacking now. I'm mostly interesting in NSMBU and MK8, though. 3D World isn't the most interesting game to hack.
These games are too similar. Like, seriously. BYAML in this game is a bit different, where some section in BYAML data is path node data, where in other types it's something else I didn't look far into.
This hack pretty much replaces Rainbow Road with Gu_Menu, which is known by MrBean as "The Void", where the last frame that appears on the screen stays there. It looks pretty cool, even when you use a mushroom.
Replacing it was quite easy, too. Just swapped files around and crossed fingers and it worked.
Enjoy.