Toolman,
Yes, I removed the heat riser butterfly valve on the right exhaust manifold and have dual exhaust. I also plan on using a 1/4" insulator between the intake manifold and the Carter 4 barrel with electric choke, on my 273. I've ordered an intake manifold gasket with stainless between fiber but I think adding thin stainless plates over the exhaust port on top of the heads is still a good idea. Most of my driving is in S. CA, but I do plan to travel.
