Long term max is a good candidate for a plot, I'll generate that when I have some time.
Might as well quantify what can be quantified, otherwise no plot. I would say that sub performance is easier to distill into a set of numbers than loudspeakers where dispersion is key and equalization is more difficult due to direct vs reflected sound. neither of those is an issue for subs playing below 80 Hz.
I picked 20 Hz as I was looking at small subs, many of the small ones cant reach 10 Hz but I will plot at 10Hz , 16Hz, and 30 Hz when I have time.