I have a 1997 Ford F-150 that I just placed a brand new engine in. The truck over all has 150K miles on it (not 100% sure if the transmission is original or not, but its very smooth and shifts well). I am currently getting 10MPG - 12MPG (12 at best even on highway), and I am thinking of going to dual exhaust (something mild, not to loud) and am wondering if it will help with my fuel mileage at all? Thanks for your input.