Use (Windows) or Keka (Mac). Extract the decrypted ROM. Crucially: Run a checksum verification. If the archive includes a .md5 file, use a tool like WinMD5 to match it. If it fails, the "extra quality" is compromised.
An "extra quality" upload will include:
To find the best versions available, use specific search terms within the archive: decrypted 3ds roms internet archive extra quality