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The indexing of spark plugs debate has been going on for many years. In fact you can buy special indexing washers in various thicknesses with indexing marks on them. There have been plenty of Dyno test's in the major automotive magazines over the years with mixed results. Some combustion chamber designs respond more than others but in all cases the gains (if any) were tiny.
As far as anti size goes, being in the ignition business, we have looked at this and our testing has come to the conclusion that there is PLENTY of ground contact through the washer or seat of the plug and it is nothing to worry about. JMHO
As far as anti size goes, being in the ignition business, we have looked at this and our testing has come to the conclusion that there is PLENTY of ground contact through the washer or seat of the plug and it is nothing to worry about. JMHO