What material do you want that tube to be made from? Then how do you want it to be made?
if carbon, you print two negative halves, lay them up and bond them. You could print the whole thing as a positive in ABS or a different dissolvable material, wrap it in the fabric, then dissolve away the form.
If vacuum forming, you print two positive halves and form over each, then bond together.
If blow molding, you print the form and see if you can get it to run the length.
If roto molding, you machine the negative halves, leave an opening for material to be added.
K&N uses blow molding for their intakes.