You almost don't need one. I haven't seen many people able to get response that good even with an equalizer! Its so good I have to ask, are you applying any smoothing? There shouldn't be smoothing on subwoofer graphs. If your sub has enough headroom, EQ could get your extension a bit lower, down to 25 Hz. That would make an audible improvement, especially with movies. It's possible you could eliminate the dip at 60 Hz as well. It would also give you the option for dialing in a house curve, if you were interested in that.Too bad I don't have sub equalizer.
Yes, that would be it. Like I said, it's amazing response you have.