On my SS, I built my 3" true duals from a Summit 3" x-pipe/true duals kit that they used to sell for $99. I had Kooks 1-3/4" stepped to 1-7/8" LT's, and I was able to use the bends in the kit, plus one or two lying around the exhaust shop, to fab a complete custom mandrel bent 3" true dual set-up for my application. 
