It's been questioned if it's even necessary, that maybe would be a reason as to their unavailability. Though I would think their would be a plethora available for the WRX, isn't the TS and the WRX the same chassis pretty much?
yes the chasis is identical. are you looking for a front, rear, or both. you can find fronts at www.mrtrally.com (STI's) as for the rear there is no need. the rear is held solid by the chasis itself because of the tailgate and design all-together. that is why you can't find a strut brace for the rear; it just simply doesn't need it.