Except my very first CH ignition module, all the rest have SynchroSpark auto advance (or should I say, auto retard ). I may not need it on every engine I have, but this way, the SynchroSpark is there if and when I need it. You never know, after I dork that Ryobi into the ground, I can always use the same module on a Poulan 46cc.

Besides, Synchrospark makes the engine idle down lower and smoother, which is important when you have a floater like a J-3 Cub that just wants to keep flying.