I replaced the standard tape head in my 94 with a premier cd deck, and replaced the speakers with boston pro series componenets in front, 6x9's in the rear.
All in all, the SVX is pretty easy to do stereo stuff on. The door assembly is not as intimidating as you might think. The depth limits on the front door components are a bit tricky, so be sure you get that right.
I'd really like to use something besides 6x9's in the rear, but unfortunately that means cutting out sections of the rear deck, then mounting in fabricated sections to fill the space.. unless I mounted 10"'s or something in the holes (heh, not gonna happen).
Anyone do anything interesting with the rears like this?