[frdmftr]

I have the dual setup that 88 Coupe refers to in his reply. Its in my 67 Delta 88 convert w/425ci. The dual is created by removing the crossover pipe, having a new pipe built from rt manifold, follow crossover pipe route and run aft alongside the Lt pipe. The crossover flange is plugged with a piece of pipe flange with the end capped and welded. The stock clamps and new gasket are used. The pipes 'split' in center of car, cherry bombs installed just before rear axle. Usual exit out rear (see pics).

Best solution would be to find a correct dual manifold setup. I know Lt side is available, Rt seems to be very rare (don't know why). If you run Rt side directly down and aft, you also need a shift rod that has a 'half-moon' relief for the pipe. There is a post somewhere here that had the info. Don't know if it was slavaged after the servers crashed.

Good luck.