I made mine.. A 2.5 inch flange from RRE, a mandrel 90* bend, and a stick of pipe, back to right around the rear doors where it goes into a flex section, a 45* bend, ~2.5 foot section of pipe past the pumpkin, 45* into the muffler.
Technically, my "downpipe" cost me about 40 bucks, and was the easiest part of the exhaust to build. The only thing thats a little goofy about it was that I didnt weld it EXACTLY straight off the flange, the flange is just slightly cocked.