Knock Sensors

RIght, most 1 wire setups are basically just a microphone that produces a voltage that varies with intensity of vibration. A knock event is seen as a large spike in that output. However, as you mentioned, some knock sensors are bandwidth specific and only respond to vibrations in a certain frequency (tuned for the engine they're being used on). I see the EFI Source Megasquirt Gold setup does have knock sensor control built in, and I know the Megasquirt can do it, but I'm curious how the EFI Source kit accomplishes that. Do they use the stock sensors or do you have to swap to a particular one to work with their system?