While the SAG thing might get you heart rate up there with a cross country runner, it is not fatal. It is a warning that plug fouling is ocurring, and action of some sort is required. Usually lead salts from aviation low lead fuel building up on the porcelain. This is the same as a low value resistor shunting the plug gap. So energy in the gap is reduced in increasing amounts until there is not adequate energy left to jump the gap. Starting with a small gap takes away the warning that SAG really is. The plug might be dreadfully fouled by the time it starts to miss fire, and then there is no quick fix to get home on. (if you forgot the box of new plugs and a plug wrench).  With a CD or MSD system the plug will fire with a giant blob of crap building up on it. On the one hand you could say this is a great thing. But eventually you need to check the plugs as part of some maintanance program. Should the plug load up completely, the CD or MSD is not going to help you, and that plug is finished. So now the fact that it ran great and sounded good right up to the instant it quit running is not a help. 

I would run an MSD on the leading plugs in any case. Let the trailing plugs show you the SAG when it develops. If you are not screaming the engine, there is no need for the super small plug gaps. Then with the gaps reccomended by Mazda, SAG give you an easy fix for more hours of power if you just tighten the gaps to go home. Or better yet put in the new plugs.  

Tracy's system might need a load of some sort or a signal transformer to prevent damage while triggering another system instead of charging a coil primary.

 

Lynn E. Hanover

 

So would a smaller gap plug reduce or eliminate SAG (sparkplug attention getter)?  Would a CD or MSD system eliminate it altogether?  Can either work with Tracy's EC-2?

Bill B