To clarify the channels: the stock P3 system utilizes channels 13 to 20 by auto select. The 32 channels give you 1 to 12 along with 21 to 32 but through a "custom" manual select. In my area, 1 to 12 are noisier than 13, 14, 15, 16. On auto, most of us see that channel 20 is the best. But the 21 to 32 are nearly ZERO activity and they are great for not getting blasted by local use.