Trap for unwary. I think there are two versions. One (cheaper) ONLY transmits stereo (one recently advertised on Gumtree). The other has 2 way functionality so you can use the microphone and interact with the on board entertainment system on Ultras etc.  

Now don't forget if you just want stereo, It can work with both rider and pillion for music.

I saw my friends install on his Road Glide the other day and he had to have two units so his pillion and he could have completely wire free communications.

I did make up an adapter cable for my bike which I just plug the normal helmet headset into (when not using bluetooth) Got functionality with and without bluetooth.

Otherwise, and I've mucked around a fair bit. Unless you specifically want to use the on board entertainment system, you'd be better off using the headset direct to the phone.

As we all know to iur dismay, there is currently NO WAY to use the current Boombox with a bluetooth headset. It doesn't have the headset bluetooth protocol (despite the fact that you can pair your phone into the bike.

I could post another pic of the cable pinouts if you wanted to adapt one for your headset.

Regards

 checked with the manufactures  about the what other headsets work with the freewire of course they said only theres ?, but would like to keep using the scala g9 if it would work with it 

From their site

Sena Free Wire Bluetooth Transmitter For Harley & Goldwing

The Sena Free Wire removes all the restraints from your ride. When you connect the Sena FreeWire to your Harley-Davidson or Honda Gold Wing, you can utilize all of the bike’s infotainment features that you love – wirelessly! Communicate via CB radio, hear turn-by-turn directions from the GPS system, rock out to your favorite radio stations and so much more – all through your Bluetooth headset. Use an additional FreeWire for your passenger to talk over the motorcycle’s internal intercom system – All with the wireless freedom you’ve been longing for.

Compatibility:

The Sena Freewire currently only supports the following Bluetooth 4.1-enabled Sena Headsets:

Sena 20S Bluetooth Headset

Sena 10S Bluetooth Headset

Sena 10C Bluetooth Headset

Sena 10R Bluetooth Headset (with firmware update version 1.3)

Sena 10U Bluetooth Headset (with firmware update version 1.3)

Note: A future firmware update is expected to expand compatibility to all Sena Bluetooth 4.1-Enabled Headsets, however, the initial firmware version only supports the 10S, 10C and 20S. The 10R and 10U require firmware update version 1.3.

Regards 

Mate spent a fortune buy the HD rebadged 20S only to find that it still doesn't pair up to the boombox. Then you have to s poo end another small fortune with the adapter.

Fuck it, I'll save my money and just put up with cable on the Ultra so i can still turn down the volume when the cook is talking but blast my Creedance.