It certainly will give the same outcome although with a slight loss in backpressure, cut it open with a saw yourself (it is pretty easy as it is not all that thick pipe) and knock out the cat material. Then take it to a shop to get it welded back up. Make sure you mark the orientation of the pipes with a marker before you cut (I used the lines of the sides of the cat) so that they can line it up in the same spot as before. Otherwise you may have problems bolting it back up if it is not in the same position. Will do the same job as a full system, albeit not as pretty and shiny
A shop will probably charge you extra for having to knock that cat material out as it is pretty hard shit, plus some just wont do it depending on your area that you live due to legalities. If you are only taking in what is literally just a pipe to be welded up, shouldnt cost you much more than 20-30 bucks.
And careful with spraying the pipes, my mate just did his and was 1200 degree F high temp paint............. let it cure for twice as long as stated.........not a pretty sight now. Mega bubbling, burning, peeling and melting. I would opt to get them ceramic coated maybe, most places also do an extreme temp ceramic coat in black if you want to go that route.
