It is almost always necessary to use a plug with a smaller gap setting when running increased boost. The additional charge in the combustion chamber dictates that more voltage is required to jump the standard spark plug gap. Options are to close the original gap of the standard plugs by approx 0.2mm, this will relieve the strain on the ignition system, meaning a smaller voltage will be required when off boost and when on boost enough voltage should be available to fire successfully and reduce the risk of misfire.
