The level with Boom Boom does not have custom music though I have tried custom music with him, and it just goes completely silent when you get to him instead of the boss music playing. Also I'm just using like..08 castle for the music, I've tried the other standard mario music too, which plays the boss music fine, everything but that little sound effect when the yellow orb drops. Also the difference between the unmodified rom and mine is, a great many things...I've used addmusic, sprite tool, carols ow sprite tool, various xkas patches I can't remember all of them, nothing related to sound, except the N-SPC patch. Other than that, I have made my own levels, used Exgfx, custom music, custom blocks, and sprites. I just made a little boss level for boom boom on a clean rom to check if the sound played on there, I figured perhaps the rom itself was messed up, but it played fine there. So somehow this SFX is not being played, or has been removed somehow. Its a perplexing problem, lol I always seem to run into the problems that have dead ends for answers, though I'm still trying. It's not that big a deal, you know, its just...it should play the sound effect its not.