Yes, the black thing is the mesh Knowles used on the Hodvtec driver for the GV. I recommend trying hearing it first without removing them and see if you like the sound before messing with it.
There is a fine balance already established with it's combination with the twfk. Removing it will add bass but might mess with lower mids also. I guess you will have to play with it.
If you remove the mesh do it carefully so you can apply them back if you don't like the outcome.
No one will help? =(
Guys who knows whether this polymer is suitable for manufacturing?
You could try to wire it first in parallel to the GK and see how it sound. From there maybe control it with a resistor only, or do a high pass filter doing so might result in dips in the response because of phase...you will have to experiment.
That polymer is for SLA 3d printing, don't think it's safe to put in the ears, also how will it react to your DIY UV curing...
Low passed X2 CI with an high passed 2389/ED?