Perfect for a heavier modified L67, these colder spark plugs are more resistant to heat than the stock plugs making them ideal for use with smaller pullies. Coupled with other supporting mods such as a lower temp thermostat and a larger downpipe these will help remove timing retard resulting from knock.  It is important to run a scantool on your L67 to ensure that knock has been eliminated. What eliminates knock on one vehicle may have no affect on another.

 

 

Copper 103's will need to be changed out a little more often than standard plugs.

 

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