For the down pipes under the hood that show, I made my own using Hearthrob mandrel bends that I sourced through JC Whitney. It was kinda fun and fairly cheap as long as you don't count your time.
pic1 pic2 For the rest of the system I took it to a muffler shop. It was very expensive, but they did It while I was working on something else. That effectively doubled my accomplishment speed.
regards,
Leon