Well, Ugetab has been showing me the way in making SNES game genie codes and I felt I should share my results. These codes are for the japanese version of Super Double Dragon. A underhacked masterpiece. These affect the music played during any part of the game. My reason for making the codes was to make a game hack of this game restoring the US versions music. The japanese version is superior in most aspects but I did not care for its music selection. So you can turn on these codes and choose whatever soundtrack you like.
Title Screen Music
D?A2-0404
Mission 1 music
D?A0-A7A4
Mission 2 music
D?27-D70D
Mission 3 music
D?2B-040F
Mission 4 music
D?24-64D4
Mission 5 music
D?20-DD67
Mission 6 music
D?30-DFDD
Mission 7 music
D?32-670D
Mission 7 part 2 music
D?36-0F04
Credit music
D?A3-0DA4
D - Double Dragon Theme (Title Screen/Great Hall)
F - City Slum (Mission 5)
4 - Duke's Hideout part 2 (Mission 2)
7 - Golden Gate Bridge (Mission 6)
0 - Duke's Trap (Mission 4)
9 - Duke's Awakening (Ending Theme)
1 - Forest (Mission 7)
5 - Cut-Scene Theme (Unused)
6 - Las Vegas (Mission 1)
B - Chinatown (Mission 3)
C - Duke's Theme (Unused)
Title Screen Music
D?A2-0404
Mission 1 music
D?A0-A7A4
Mission 2 music
D?27-D70D
Mission 3 music
D?2B-040F
Mission 4 music
D?24-64D4
Mission 5 music
D?20-DD67
Mission 6 music
D?30-DFDD
Mission 7 music
D?32-670D
Mission 7 part 2 music
D?36-0F04
Credit music
D?A3-0DA4
D - Double Dragon Theme (Title Screen/Great Hall)
F - City Slum (Mission 5)
4 - Duke's Hideout part 2 (Mission 2)
7 - Golden Gate Bridge (Mission 6)
0 - Duke's Trap (Mission 4)
9 - Duke's Awakening (Ending Theme)
1 - Forest (Mission 7)
5 - Cut-Scene Theme (Unused)
6 - Las Vegas (Mission 1)
B - Chinatown (Mission 3)
C - Duke's Theme (Unused)