I had a full system on my old Vectra ,i wanted it not too loud so they made a large back box .It kept breaking at the gable/end of the box ,i took it back a few times to get fixed they put bracer pieces from the pipe to the gable/end ... In the end i asked them just to make the box smaller as he said it was too heavy for it to hold between the hangers .
All above done with no fuss or charge ..