Since the timing on our cars is computer controlled, how do advance/retard devices work? ie - BTM's or digital 6's that retard timing on boost or nitrous, etc.
as i understand it they work on your "base timing" which is what you are adjusting when you pull the spout connector and turn the dizzy. the computer then makes the adjustments from there.
Ignitions take control of the signal from the computer to the coil. When a boost source is plugged into the ignition it can then retard the timing based on the amount of timing retard dialed in. An aftermarket ignition is like a chip you add to your computer. The computer still "controls" the engine, but the chip is making it operate under different settings.