Manifold Duals ???
I agree; duals off the exhaust make more sense for a street car.
I am LAZY and took my car to the local Midas Muffler in Albany,
Ed did an Awesome job,
all I supplied was the Dynomax Super Turbo mufflers and the 1969 Dart chrome tips.
Make sure the passenger side flapper isn't froze shut.
http://www.youtube.com/watch?v=Ud8mci4rjFU