Question about buying Carter BBD for my 318 (unless I should look at something else)

It's a tried and true combination, I've run that set up on 273's, 318's and mild 340's. I almost 99.99% of the cases, the fuel economy was better than any 2 bbl on the market. You will see no difference at a cruising speed at 2500 and under. You will see more and better performance when you plant your foot in it.