You do realize that STI stands for Subaru Tecnica International, yes? The STI designation is given to the WRX STI as a special model of the WRX that has been tweaked by STI . . . So really an STI shirt is not a promotion of a single car, ie, the WRX STI, at all. It would be akin to a Nissan owner sporting a Nismo shirt . . . which, by your logic, is apparently verboten unless one owns the Nismo 350z, and all Nismo apparel prior to the release of that car should not be worn by anyone

So . . . your argument is pretty weak. And, "not trying to be mean," but is it necessary to act like a dick about a T-shirt you purportedly have no interest in? Or, really, a fucking T-shirt in general?