If you want to watch a boring 20 part series on how I built my exhaust system, you can start here:
The cliff notes is that the system is 2 1/2" off the manifold and necked up to 3" out the back. It uses a pair of glass packs in series to eliminate any droning. The manifold itself was gasket matched to the gasket and the exit was opened up to 2 3/8". This makes for a fairly quiet and free flowing exhaust system. This engine will eventually get a turbo, so I didn't want any back pressure in the exhaust.
It would be nice if Summit/Jegs would just sell you half of their V8 kits, but they won't.