Interesting, I have a pretty similar notch at 110K, but low end extension is quite different - originally based on the Sonarworks (UI) correction graph but then extended far deeper. It sounds excellent to me.
Do you have anything that can load VST, RTAS or AAX plugins? I'd like your opinion.
I take your point about variations, that's partly why I didn't make any deep changes to the mids/treble as I expect they're more prone to variation, although I still plan to look for specific sharp resonances (but those are apparently unique to every ear). The low-bass recovery should be quite universal though, Sonarworks definitely restored the rolloff I heard on lower bass notes, I just found you can extend it much lower than they do.
I just based my adjustments off the graphs online as I can't take a proper measurement. Even if I had a mic and an RTA (I do, but for the car), it needs a mannequin head to simulate on-head response, ie, how the response is when the earpads are on the head, essentially locking an area where you can get some resonance as opposed to just hanging a mic between the two sides. Even those mannequin heads are manequins - ideally they'd have to be ballistic dummies (like those you see on crime shows when they try to recreate the victim's injuries) since human flesh has a different acoustic properly than plastic.
In my car though since you don't have to take into account simulating earpad interaction and resonances what's important is to get the mic where the driver's head will be, but nowadays that's mostly all that's needed since even my new processor comes with its own auto-calibration program and test tones. it will take a lot of the trial and error out of time alignment settings, and from my own experience, a lot of the peaks or dips tend to be due to timing issues than response issues per se, so to the ear it gets very close to the smoothest possible response just by dialing in the right tweeter amp to midwoofer amp gain settings and time alignment.