I recently installed a sub in my 07 TL-S. At first I was getting some horrible feedback noise when at idle. I found out that I needed to disconnect the rear noise cancellation microphone because it uses the stock sub and with an aftermarket sub the sound is increased 10-20X. So after disconecting the noise cancellation microphone my HFL does not work on incomming calls or when playing messages. It worked before. This is with the an Iphone 3GS.