Originally Posted by
mech986
Ivica gave you the port lengths for a given port inner diameter. These dimensions give the volume and mass of air contained in the port which affects the port tuning that defines how the cabinet interacts with a given woofer.
since your cabinet is a lot smaller than the 4355 cabinet, the internal volume is also a lot smaller, and requires tuning with the ports to achieve the same relative tuning with the much larger 4355 cabinet. One can also tune lower or higher and introduce artificial electronic EQ to extend the response lower if needed at the expense of power, a bit more complexity, and potential overexcursion of woofers in question.