Hi, some mystery tracks from 1991:
01 - at the start something similar to "systemosis" but I never found the ID of this track. I found similar type of sound in the classic The Kick Squad - Soundclash (around 20 seconds mark)
Found! Mr. Moses - Sound And Vision (Instrumental Mix) - Thanks Kammie & Brady!
02 - X-Es - Roller Coaster - Thanks dc-123!
03 - some mix of "Phantom of the Opera" (Harajuku) or a mashup of two tracks? I went through tons of Phantom remixed however could not find anything like this mix
04 - Platform One - The Desires (99.5 Remix) - Thanks elimix!
Thanks for listening!