You still have warranty on your 2001? Must be extended warranty. Get the dealership's bodyshop to put on the bumper, it will have some sort of warranty if they do it.
Almost any dramatic bumper (even the EVO I would imagine, better check that out) will require some modifications behind there. I got a friend what went with a stock RS bumper from european-parts and he had to cut some major steel out of the front, grinding and all that.... it's the way it is.....