Apologies if wrong...It may be incomplete to state the purpose of the new passive radiators (with the CDWG) is to match the lower overall output resulting from the CDWG slot. The lower overall mid & treble output can be corrected by simply turning the level controls up about 1.5dB.
There is a secondary effect of the slot. At 20 kHz, the CDWG increases the dispersion to 180-degrees, & a 6 dB/octave low-pass filter effect is introduced with a 10 kHz pole.
A classic treble control (remember those?) boosts or cuts 6 dB/octave at 10 kHz. Turning up such a control will correct the CDWG treble rolloff. Important note: Digital treble controls in modern components are bypassed in "direct" & pure analog modes (phono, SACD, DVD-A, etc.).
Barring a treble control, a less accurate but practical solution is to increase the speaker's bass Q. This will make the the bass curve above the cutoff peak look like it was high-pass filtered, thus balancing & complementing the CDWG low-pass filter effect in the treble.
Probably the PR Q is increased via stiffer spider &/or surround, providing quicker response & less overhang than simply adding more mass.
