The Fuel Meter Unit helps to move the fuel back in the return side to
the tank. They are calibrated for your injector size for a very good reason.
It is only necessary with the smaller injectors because you need a larger LPH
fuel pump to keep up with the fuel needs of the supercharger.
With the smaller sized injectors they can't use all the fuel that is being fed to them
so it would back up in the rails if you didn't help evacuate the suplus
un-used fuel back to the tank as quickly as possible. This is how it was explained
to me and it makes sense.
I found on a Ford Racing Catalog on Disc for 2009 a handy guide for proper fuel injection
sizes by approximate horsepower ratings, it's on the money for proper fuel air ratios.
You may then tweek your fuel pressure up or down to get the correct "Stoic"
reading on a Wide-band Air fuel gauge. I use an Autometer and it works well, just make
sure to get the Wide-band one and "NOT" the Narrow-band one. You will know the
difference by price the Wide-band is around 260.00 but they are coming down in price
the Narrow band is 50.00 or so and all it will do is bounce back and forth because it is
only designed to read slightly around "Stoic" where as the Wide-band
covers a much larger range. If you want to completely tune your car you can
look into an Anderson PMS system that will do alot more Fine tuning. You can adjust
everything from timing by boost and fuel adjustments by injectors pulses by Percentages etc..