Need your help on 383 Dart exhaust

i took a customers car to my muffler shop with the x pipe and extensions he got from jegs, and it was so thin that when they went to work with it, it split. all i was saying was that their pipes are thinner wall than what you get at a good reputable shop.
That may be true. There has to be some reason that they can do a system for well under half the price that a shop can.