Looks like someone mentioned this a while ago and it got buried, so I'll just ask again here.
Maui Mallard refuses to boot on my Japanese Mega Drive because of the region lock. It only got a PAL release and it tells me to go to hell because I don't have a PAL Mega Drive. The MegaSD's auto region thing doesn't work at all for this game on my Mega Drive or my Mega Sg, and I have to use the Mega Sg's region settings and auto-detect to get it to run.
With the Mega Sg, you can do a few things with this game. You can disable the auto region detect, boot the game in PAL mode, and then force it to NTSC, which more or less breaks the game, but it also has a built-in cheat system that you can activate before you run the game from the Mega Sg's SD card slot. EAAT-BL1T forces games to run in NTSC-U mode, and it also lets you both launch and run Maui Mallard at 60Hz without breaking it. There are also equivalent codes for PAL and Japan, but I don't know what those are.
If you enable the Mega Sg's auto-region detect mode, boot the game, enter the code in the MegaSD's cheat menu, activate it, and hit reset, you can run the game at 60Hz in NTSC-U mode. Set the region to Japan before you do this and when you highlight the auto-region setting option in the Mega Sg's menu, you'll see it specifically says forced region: USA.
Obviously you can't do this on a real Genesis or Japanese Mega Drive because you can't get to the cheats menu without entering the game, and the MegaSD menu doesn't seem to work on the screen that tells you the game is PAL only. You'd need to be able to enter cheats and activate them on the MegaSD's main menu before starting a game.
Anyway, this would be interesting to see and would help people who don't have a Mega Sg to play some region-locked games that the MegaSD isn't capable of fixing.