This is what the inside of the intake looked like;


My research indicates that a tube with a bell mouth will flow at least 30% more air than one without. To their credit Ford had rolled the shoulder a bit at the tube entrances. I opened them up as best I could with the material thickness there was.


From what I read, polishing the surfaces is counter productive. Boundary layer air clings to smooth surfaces and actually creates more drag. Rough surfaces cause the air to tumble along the surface and flow better. ie Golf balls have dimples to reduce drag.