I filled up today and did the math and i got in the neighborhood of 6 mpg on my last tank. I dont drive what i would consider hard. Here is my setup. 305, 32 in. tires, 3.73 gears, headers, 3 in. single exhast, k&n filter, stock carb, 700R4 tranny. The tranny tends to upshift a little too soon in my opinion and also does not like to downshift when it probably should, without really stomping the pedal. I do a lot of city driving. Could my stock carb be the problem? could the weak 305 be struggling and giving my terrible gas mileage? is the exhaust too big for my engine?