I got rid of the backbox on my Toledo today .
I just chopped it out, welded in a straight piece of tube, made a couple of hangers, and fitted a twin pipe trim on the back. Cost a grand total of £30.
When driving normally I can hardly hear any difference, but when I boot it, it sounds louder, but it is a nice deep loud sound.
Its also made a noticable difference to the performance as well, though I'm not surprised, as it was full of crap.