The iphone bluetooth stability issues are to.do with the phones design itself. The problem is the wifi antena is right next to the bluetooth antena and it causes interference if wifi is switched on. Switching the wifi off will help with bluetooth stability but will not entirely prevent iphones dropping out. All manufacturers have this issue as apple is not very friendly with sharing software etc. The bpm (bluetooth phone module) is vin coded to the acm (audio control module), fdim (front display interface module) and aim (audio interface module), therefor all 4 modules MUST contain the same vin number for the systems to work, hence the need to program the new module