You will see a better result from improving aerodynamics, I ended up removing my WAI because the engine was retarding the timings when I had to stop (It has been in the 80's where I live)
I did an upper grill block and fixed my panel gaps to compensate for any FE loss.
Just to be clear, when operating normally, your throttle is mostly closed to form a very small opening to the intake manifold. It is by far the most restrictive thing in your air induction to the pistons. So creating a "freer flowing" system up stream will do nothing to improve airflow at the 10-20% power which is where you operate 95% of the time. Any claims of better mileage are not supported by reason and will not be seen in real life. As others have said, reach for lower hanging fruit if you're looking to achieve better fuel economy.