I did the intake mod on my 2000 5.4l yesterday. I used 3" pvc pipe and removed the snorkel. Used a table saw to thin the pipe OD out to fit through the fender hole. The old snorkel OD fits inside the ID of the pipe that I used. It was a little tough getting the airbox back into place. I wonder if that's why they factory necked it down so much, to allow ease of assembly. The pipe is attached to the airbox with a 3" to 3" fernco.
Pretty easy but messy thinning the pipe out. Looks clean too. You can't see the white PVC, just the fernco. If you search the web I think it is "gotts intake mod" or something on another site. I can now see out into the fender looking through the box. I can fit my whole hand out into the fender. Much bigger opening now.
GP