I have the 4000NEX in my 2012 Lexus CT200H. Very impressive unit, except for the background noise during phone calls. The 4000 microphone sensitivity seems quite high, and even when driving on "quiet" roads people on the other end of the phone say the call is quite noisy ... to the point where I have to switch to my iPhone 5s with earbuds in order to have a chat with someone. Anyone else experiencing similar issues or have advise? In trying to troubleshoot the problem, I have relocated the microphone from the windshield to below the steering wheel. I also have the mic on the lowest volume sett