Most 3DS ROMs will be in .3ds or .cia format. Avoid any "ROM" that downloads as an .exe or .zip containing suspicious installers.
Your (Original 3DS hardware or Citra emulator) If you need help finding the specific patching tools If you are looking for performance optimization settings shin megami tensei iv undub 3ds decrypted rom free
The safest and most ethical method is to dump your own SMT IV cartridge using a hacked 3DS and apply the Undub patch manually using tools like LayeredFS. Key Features of the Undub Experience Most 3DS ROMs will be in