This will not improve the off-road ability of your JK in the slightest, but I find it really useful.
I found that my Bluetooth headset and a couple of cigar lighter plug-in Bluetooth systems I tried were just not loud enough for me and they didn't do anything to mute the radio either. I know there is some discussion of just adding a U-Connect module, but I couldn't find anyone that had done it to say if it would work or not rof sure. So I installed a Vizualogic CigBlue
It doesn't have a display for caller ID and is not the cheapest system around, but it is pretty seamless and clutter free, and gives a close to OEM look. It's not for everyone, but for me it was the solution I wanted.
The JK radio is controlled by the CanBus so there is no mute wire or Acc power wire, which makes muting the stock radio a little more difficult than just hooking up a wire, but it can still be done. I ran the power to the stock amp through a relay triggered by the Acc Out of the CigBlue. When you make or receive a call, the CigBlue cuts power to the Acc Out circuit, which in turn opens the relay contacts and cuts power to the amp. The radio head unit remains untouched and is still powered on. Once the call is finished, the amp gets power again and sound continues as normal.
I mounted the control unit in front of the steel plate behind the panel below the steering wheel. I used the factory cigar lighter mounting hole for the CigBlue control button, which is back lit blue, but you could mount it anywhere. I mounted the microphone on the edge of the upper center console, as I wanted it away from the top to minimize wind noise.
It works great and the adjustable volume can be set very high (up to 20w). I can use the voice dial feature of my phone, and it also does redial of last number dialed.
The factory amp can be found behind then panel below the steering wheel. There are two connectors to it, a 16 way and a 22 way.
On the 16 way the front drivers side speaker can be found on:
Amplified Left IP Speaker -
Amplified Left IP Speaker +
On the 22 way the power is on:
Fused B+ IOD
You will then also need a Battery + (which I took from the 12v Power Outlet), a ground and an Acc On (which I took from Connector 22 Terminal 12).
This isn't for everyone, but for what I needed it works great.