From my point of fiew the antenna delivered with comstation has a design flaw. For best ADS-B (1090MHz) reception remove the radials and the top part. That way you will lose VHF reception but ADS-B reception shall improve. GPS shall be working too, as it is received by a third receiving part integrated in the antenna.
If you apply a 1090MHz narrow band filter the frequencies of VHF (ATC: 117,975 to 137 MHz) and GPS-L1 (1575,42MHz) will be blocked and therefore no reception is possible.
By the way: Why have you blacked the Firmware version. I understand the reason for blacking Station ID/Serial number, but blacking the firmware revision doesn't make any sense, as several boxes will use the same revision.
Ingo