Ok let's do a sim. Here's the inputs. All inputs are in metric so I converted them, you can check my math. These are the t/s and enclosure dimensions you wanted me to use. Forget the Xmax and Pmax in the screenshot on the left, I'll set that later. Power for this sim is set at about 135 watts.
Here's the system schematic, the frequency response and cone excursion.
Note that the port is almost as large as the chamber by volume.
The blue trace on the frequency response and cone excursion graphs are the results of a simple sim, the red trace on those same graphs are the result of factoring in estimated effects of lossy inductance. I can point you to volumes of info on lossy inductance but for now you can rest assured that the actual measured response of this sub will be somewhere between the blue and red traces, closer to the red trace. For this reason all subsequent sims will use the red trace model with lossy inductance factored in.
As you can see, this power level causes excursion to reach xmax at the excursion hump above tuning. The excursion spike below tuning can be taken care of with a high pass filter or ignored in design and worked around by just turning down the volume knob when stuff starts to sound bad.
The spikes are dips above tuning are what port resonances look like. The very narrow ones won't show up much, if at all. For example, the spikes and dips that are just one pixel wide won't show up at all so you can round off these spikes and dips mentally a bit to imagine how they will actually measure in real life. The wider parts of the spikes and dips aren't gong anywhere though. This response is actually not that bad because the driver and port are centered on the chamber - it could be made better or worse by moving the driver and port locations around, but because of the small chamber size there's not too far you can move them so you are limited in what you can do by driver and port location.
Here's port velocity and group delay without any filters applied. Note that the higher resonances definitely affect both at frequencies where they appear. Also note that at the lower frequencies it will never actually get that loud as shown as excursion is pushing 60 mm near tuning.
Now let's add a high pass.
Top row - frequency response and cone excursion, dark black trace is with filter applied, light grey trace is without filter
Bottom row - port velocity and group delay with the filter applied
It becomes quite clear that if you do use a high pass filter and keep the sim at this power level, the filter completely chokes off the port resonance. Spl at tuning drops about 12 db, port velocity drops all the way down to about 5 m/s, both of these indicate that the port isn't doing much of anything, the hpf completely castrated the port output.
Whether you use a hpf or not, your output at tuning is going to be limited to about 83 db or a bit lower at 6 hz, any more than that will exceed xmax, with or without the hpf. 83 db at 6 hz won't produce anything at all in terms of audible or tactile output but it may produce a bit of distortion and mechanical noise. Add another fully powered sub and you get 89 db total - still not going to be noticeable except for distortion and mechanical noise.
Also note that the hiphpass filter has caused group delay to rise up almost to the 400 ms mark, not that you will likely notice that at 6 hz.
Now let's compare this design to a comparable sealed box design with the same driver. I pushed the sealed box size up to 154 liters (same size as the ported box was including the port volume) and turned to power down a bit to 105 watts to keep it within xmax.
Black trace is the sealed box, light grey trace is the ported box with high pass filter engaged.
Frequency response and cone excursion shown.
So what did we gain with the ported design? Looks like about 3 db of gain from 6 - 20 hz and then a messy frequency response above 20 hz. And a lot more group delay (if you care about that).
This is what I was talking about - resonant strength is dictated by enclosure size. Your enclosure size (~154 liters, port included) is not nearly large enough to produce much resonance at tuning. So there's only a negligible difference between the ported box and the same size sealed box. As I said before, for single digit tuning I'd move up to at least a couple of 18s and bump up enclosure size to at least 30 - 40 cu ft per driver if you want any real output at tuning.
No matter what box type you choose - ported, bandpass (all types, 4th, 6th, 8th order, including ABC), transmission line, tapped horn, front loaded horn, etc, it doesn't matter, you won't get any more output than this at tuning unless you make the box substantially larger. The more complex you make it the more resonances you will have to deal with in the passband but it won't get louder at tuning no matter what you do unless you increase the box size.
That concludes our simple ported sim. I've got tons more to say about all this but no time right now.