Sounds like you don't have one.
Low end is enhanced on any drum with kick port. KICKPORT operates on the tuned-port principle, and it works. An EQ pad or any weight against the reso will not yield the same results.
Mic KICKPORT and its effects are undeniable.
Having been a speaker builder for many years, and having made a number of ported speakers, I know how the "tuned-port principle" works.
Designing a ported speaker involves a fairly nasty formula. Into that formula you plug in bunch of driver parameters plus the internal volume of the cabinet, and it gives you the diameter of the port and the length of the tube behind it. The volume of the cabinet is a constant--if you change that you get different values for the port dimensions. (It's worth noting that that formula only gets you in the ballpark: you have to tweak the port's dimensions and tube length to suit, all to gain a few dB of sensitivity and about 1/3 octave of bass extension.)
Therefore, if the Kickport is indeed operating on the "tuned-port principle," it can only be correct for one volume of air. Other volumes--which is to say, other size drums--will predict a different port.
That makes sense: some guys report good results with the Kickport, others not so much.
Therefore, while I'm happy you like the Kickport and that it works great for you, your results are not necessarily predictive, at least not to the extent that "Low end is enhanced on
any drum with kick port." That it works for some is a good thing. Might even work for me! Dunno! Alas, your experience is non-transferrable.
And not to be snarky, but the surest way to lower the pitch and reduce the sustain of a ported reso head would be to hang a weight on it. A weight, say, about the same as a Kickport.
Just sayin'.