The results of the port noise calculations are thus:

Minimum Diameter = 5.81 inches

Minimum Area = 26.51 inches

Length of a side for a square vent = 5.15 inches

Since I have more of the 2.25" tubing, i was thinking the easiest way would be to take the tube that's in there out, and add two more round ports. When i enter "three round ports x 2.25" each" into the port length calculator, do i enter the "Desired Port Diameter" as 5.81" or 2.25"?

Is the resulting number for EACH of the three ports, or do i take that number and divide it by 3 and do that length for each port?

This is all assuming that the 3x 2.25" ports will indeed NOT have port noise since they equal larger than 5.81" total...right?