Interesting. I haven't tried different phone positions - I usually put it in the cup holder or the cubby under the HVAC controls in front of the shifter when I get in the car. What position have you found gives the least BT noise?
As to the mic issue -- I had planned to simply replace the whole thing with my own mic / board. I haven't gotten around to this because the foam seemed to make the mic much better in my car on the roads I drive on my daily commute. My family no longer complains when I drive to / from work and call them. I strongly believe this noise is largely caused by the road noise and a unidirectional mic would fix most of this. Now that it's bearable for my family with the foam in place I'm not as motivated to replace the mic. When I convince myself to do it, I'll post up.