I don't have a MP2 ISO, so I can't say for certain. However, the set I have also has 84 files (chances are that the one I have is the same as the one you have. I uploaded a fair amount of DSP sets). If MP1 is anything to go off of, I'd say that the missing song(s) is(are) probably in some other wonky format (MP1 uses RSFs for the "load game" screen, and the credits, as well as 2 other tracks that I can't remember the names of). If I get the time/bandwidth/space/bored enough, then maybe I'll download the MP2 ISO, and see if I can find anything else that looks like it might be audio. If not, then maybe I'll hunt down the MP2 (and MP1) OST in a lossless format, and convert the "missing" songs into ADX...
Anyway, it looks like you might be right. If the title theme isn't present in your set, it's probably missing, and therefore is quite possibly in some format other than DSP (which wouldn't be a first). Mouser X over and out.
84 here too. I'm going to hazard a guess that the audio is stored in the video file that plays in the background of the menu screen(It does that right? I can't remember...) or something weird like that... If I have time, which I probably won't I'll see if I can see it in my MP2 game dump. (I can't redump the disc since my Game Cube is with my mum... only got my Wii here now :))
CRAP: Seems I don't have the ISO handy afterall... nevermind then...