Hi Alex, yes I understand how the wasted spark system works, but I installed a wasted spark ignition in my car over a decade ago, and have not found any issue with spark plug erosion.I mentioned this in post #41 above, in a waste spark coil there is a plug at either end of the High Tension coil which is what changes the polarity of the second plug and thus changes which part of plug erodes.
Note: this polarity change does not apply to Richard's GTi6 as it has four individual coils, though with two coils drawing current through one driver it possibly may current limit and not get fully charged in some instances.
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I've since found info from NGK.
Waste Spark Ignitions - NGK Spark Plugs
If you drive a car from the 1980s, be aware of the waste spark ignition and what that could mean when you are purchasing replacement spark plugs.ngksparkplugs.com
PeterT's comment implied that there is a performance issue with the reversed spark direction; I was wondering if that really is so, and why would it be? After all, millions of cars had such systems OEM for some years. (That said, I just realised part of my question for Peter makes no sense, as the 'reverse polarity' spark will be firing that cylinder on each compression stroke).