I just got a 2000 Expedition with a 5.4 trition and found and intake in the bone yard, like this one in picture. Are they an upgrade to the plastic intakes? Mainly performance wise?? Saw it in bone yard when I was getting misc interior pirces and was juts wondering if worth getting???
(found this picture online)

 

Plastic intake manifolds are smoother internally and generally better for performance. Also the plastic is lighter. The problem with them is that they can crack in some applications. Aluminum would be better if you were going to port and polish internally.

George