I got my brake rotors from here:
http://www.r1concepts.com/subaru-svx-1994-4wd.htm
They are very good, I like them a lot, and they're very good for the price. Get the "premium" ones of course. (I used the premium up front and the regular ones in the back). The DBA (disc brakes of australia) I have heard very good things about here on the forums, but it seemed like a hassle trying to find out where to get them from.
I also used EBC redstuff brakepads, and I really like them as well.
Also superblue brake fluid:
http://www.tirerack.com/brakes/acces...tail.jsp?ID=21
Or the yellow stuff that's the same:
http://www.tirerack.com/brakes/acces...tail.jsp?ID=22
What many people do is just alternate the yellow and blue each time they change it that way you can tell really easily when the old fluid is done coming out.
Also SS brake lines are great, I got some of the Ebay ones for like $60 and they feel great.
And adjust the brake pedal so that there is less free play, just because it'll feel better.
Grippier tires = more
useful stopping power. Once the ABS kicks in, the biggest brakes in the world aren't going to stop you any faster. They will, however, handle the heat better, but the rotors and pads I linked should handle the heat very well. I think two-piece rotors would be even less likely to warp from heat, but I don't know if there are any that fit the SVX or how expensive they are.
I haven't gotten it to the track yet, but my setup handles my spirited driving really well, and has handled my brother's borderline reckless driving just fine too.