lol... You have the option to buy it pre-assembled (ie: the 2 parts welded together) OR separate. There are almost no advantages to buying it separately unless you can weld yourself.
Good luck pulling it out, but this may not be very effective as I bent mine when my mate stuck mt Cinq in a wall, albeit at like 5ishmph - but the damage was quite bad - ended up having to get a new slam panel, have to old one cut out, painted and put back in. The garage won't like doing it either I would imagine because it's a pain in the arse to do and takes a while.
If you can live with the fact that it's wonky and that the bumper may not fit properly, then you may get away with it... All depends on how bad it is really...
BTW - small tip that may help to pull it out. Get hold of a barbell (one of those things you do bench presses with in a gym) and a strong bloke and it is possible to stick it between the slam panel and the manifold/engine and then lever it back into position... ish - this was good enough to keep me on the raod for a couple of weeks before I got it replaced.
Hope that helps,
Matt