Because nobody ever really understood how trainer music was determined until now, and it seems like a useful feature to have. Alright so for this you're gonna want to extract your rom and decompress a couple of the files. I normally use ndstool and blz.exe to do this: ndstool -x originalromname.nds -9 arm9.bin -7 arm7.bin -y9 y9.bin -y7 y7.bin -d data -y overlay -t banner.bin -h header.bin copy arm9.bin arm9decomp.bin blz -d arm9decomp.bin copy overlay\overlay_0036.bin overlay_0036decomp.bin