Changing the size (typically the length) of the port-tube you can change "tuning of the WHOLE SYSTEM", (box+port resonant frequency Fb) and what would be the influence of such (tuning or changing) to the WHOLE SYSTEM RESPONSE, you can easily see using mentioned simulation programs.
Here are some examples:
it seems that "what-ever-you-do" you will get -6dB around 30Hz....
so it seems to me that optimum in maximal cone displacement "in band", and "out of band" would be the 'leading rule'.