BASF Heavy Industries (Subaru Division)
There's a little handful off the top of my head. There's a lot more than 3 major manufacturers of swaybars, though a couple of those names are going to have duplicate parts, SPT outsources it's race parts in cases like this. JUN will either sell you one for big dollars, or question your goals and point you at an off-the-shelf race bar.
Remember also that stock struts and springs are ugly on a high performance swaybar. They are divey and soft. With the travel limited and the deflection increased, the roll will be harder to combat, a coilover with variable damping is good idea.
Accuracy of alignment is of huge importance w/ swaybar upgrades, since the tires' contact patches will be applied more aggressively. If they are not straight, the contact patch will be more of a "place where the tires wear out", and not something that sticks to the ground in tight corners.
It's awesome to see so many enthusiastic people who want improved handling, but don't just get one piece of the puzzle and expect life to go on without any hassles. It's expensive, and really doesn't start to work until it is fully built. Only then can it be balanced and adjusted to create a total inertial singularity. Out of adjustment, these are some hairy cars to drive. When tuned right, on a good selection of coils, dampers, bars, links, control arms, bracing, and bushings, they are some of the best handling cars in the world. Lightweight and all-wheel-drive are something that don't come together often, but together, area good reason to research what ought to get done first, and swaybars alone are not going to help. The stock rim and tire, damper and spring/coil. brakes, brake lines, fluid (OE), and chassis bracing are not enough to deal with the shock. If you replaced your endlinks w/ the aftermarket ones that match your bars, it will be even worse, as your plastic ones reduced impact on the mounts. STi and a bunch of private companies have control arms and pillowball leading links, most are adjustable. Adjustable front endlinks are getting popular, as are rear upper camber plates for pillowball coilovers.
I am waiting for one myself. I want to install a Tein EDFC on Hyper RSIII coilovers. The knobs and motors fit, and the mounts are great, it will work, but not until HKS or Tein is willing to machine a rear adjustable upper camber plate. Or until I find someone who will do it. I have a price limit of $200 for the pair, and if you want to make more than one set, I guarantee there are a lot of suspension junkies that will want them. Blue please? (j/k)
That's my WRX, just started fiddling with the engine, Borla turboback, HKS intake, Optima battery, PNP'd OE turbo, GReddy RS BPV, Cusco OS bar, Hyper III RS coilovers, polished intercooler, tons of blue silicone, IC sprayer, etc., etc.
That's my previous car... suspension was:
KYB GR-2 struts
Eibach ProKit springs
KYB upper strut mounts
those wheels have been moved from one car to another... they are indestructible. Light and strong is an odd combo, but they are cheap, so if you are looking for wheels, Motegi's FF-7 is rock solid.