Teagues has it. I think maybe MRT makes it. I believe I once saw an improved, more powerful, master cylinder once but forget where.
WRX parts are so expensive now. I feel like a victim every time I buy something. $250 for slotted rotors? That's nuts!
I spent a lot on improving my brakes and would like a simple fix. I've got steel lines, EBC slotted froont rotors, stock rear rotors, and Porterfield pads. I never measured my stopping distance but wish I stopped a lot better.
I believe it was the June issue of Sport Compact where they compared a big brake system to stock. Probably spending a bundle and did NOT improve 0 - 60 stopping distance.
Of course, on a race car, you'd also probably want to scrap the brace(unless rules don't allow brake changes apart from pads in your class) and opt for a dual cylinder for front/rear with a balance adjuster(which isn't too expensive either).
There were some fitment issues w/ the original MRT brace, evidently those have been fixed (unless one was unlucky enough to get an old one). This bracket simples takes some of the flex out of the master cylinder where mounted in the firewall. If you've already replaced pads, fluid, lines it would probably be worth a try.
As I suggested above, for a similar price, you could go with a metal dual cylinder instead. In Canada, the prices of the brace is much below the US...basically we can often get that exact part for $70CDN....but if shops are charging $70US...you might consider going all the way with the metal duals...then you'll have no flex, plus front/rear adjustability.
I installed mine because I saw how much the brake master moves when hard braking. Next time you bleed your brakes watch that thing flex thru the firewall! The bracket is tough to install because of the limited space, but mine fit fine. Pedal feel at the track is a little better, and I think pads & lines would make the stock brakes more than adequate with the MRT bracket. I paid less than $70...got it from Prestige Subaru in N.C.
Any company that makes a full line of brakes would offer dual master cyls. Wilwood for example has several versions(I believe) that are quite cheap(not sure, but I guess try www.wilwood.com). There really isn't too much detail to tell, just that they are generally made from metal, have two cyls(duh) and a balancer to adjust the percentage.
Well I just went to the Wilwood site. Here is basically what I'm talking about.