Manifold Duals ???

what is the outlet of the manifold? for flat outlets i just make my own out of 1/2" plate, torch cut them using a gasket for a template, 1/2" or even 3/8 is thick enough that it wont warp when cut, welded or over tightened. if it is the cone type you should be able to just go to a muffler shop and have them make you little stubs with the cone flared and flanges. if you can build the rest of the exhaust this should be no issue. i just buy a few mandrel bends and a couple sticks of pipe and go to town. i havent used an exhaust shop since my first car.