I agree you will get better milage with the 2 barrel, the single barrel carb is always working at 100% But with the new found power you will be in it a lil more too ! A couple of people have told me not to get headers for my dart, why is that?
If your Dart just has a standard slant six with no performance upgrades, then getting headers is just kind of a waste. I don't know what the actual figures are, but it's just one of those deals where its like is $600 worth 5hp on a stock engine? It's kind of like getting too big a carb for the motor. Bigger isn't always better unless you compensate for it by doing performance upgrades to the engine.