Just tried the GangstaKANG version for the Bluetooth support
I can confirm the Bluetooth is indeed working (at least it's enablable in Settings) but I was unable to get it to see my car stereo. Pressed Search for devices, there was no visual feedback (can't remember if there's meant to be) and nothing appeared in the list. Enabled visibility on the phone so that the stereo could possibly attempt to connect with the phone, still no banana.
I restored the 4.1 KonstaKANG and was able to pair without issue.
I upgraded from KonstaKANG 4.2 from the 6th January, flashed the zip provided by Gansta on the previous page. I did not wipe data or cache. I didn't do much playing about with restarting, enabling Aeroplane Mode etc, although I did attempt to turn Bluetooth off and then back on