340 - Stock Exhaust Manifolds or Headers

Headers are always better. The engine breathes better. Longer individual tubes on each of the exhaust ports makes even a stock engine a better engine.
I put a Header on a 2.4 4 cylinder and it woke that 93 hard body truck up. If you really want more power out of a stock or barely above stock engine
shorten your exhaust system.This will cause less restriction and more Torque and torque= horsepower. I've had A-bodies with exhaust coming out in front of the rear tires and that 340 Duster ran like a raped ape out of hell. Keep the original exhaust manifolds and store them away but run headers and shorten exhaust system and you will make power and can be budget minded at the same time.