technically they will bolt up -- we have the same car
but because the rear unibody lacks flares, the bumper will stick out and look weird
you could bolt-on pretty much any part, including the bumpers, sideskirts, and front fenders from an STi ... but you'd still need a way to do the flare in the back -- this would require cutting and welding in new metal.
I understand that it would require fender flares, I just want to know why these companies selling the bumper are trying to tell us otherwise... Oh and on the same note of front fender flare with no rear. I saw an 2.5 RS today that had front flare but no rear. Looked clean but horrible due to the fact rear was small.