Could I assume that if my port opening (which is 2” x .78” on the primaries) consisted of a inside perimeter of 4.89” and an area of 1.43 square inches and I used a tube with an internal diameter of 1.55 inches (for a total area of 1.9 square inches) and then changed the shape of the tube to mate with the port dimensions, that the reduction of area from 1.9 s.i. to 1.42 s.i would in effect achieve the tapered effect you referred to below?

 

Tom Mann