Hi, i think you will find that the NGK plugs have a preset gap, they are not adjustable. I went on the NGK website ages ago and am sure that is what they said. If you find a local stockist of NGK plugs, who is good, they should be able to verify that. Hope this helps, Damian.
P.S. NGK plugs are good, used them in my Primera for 12 years, never had any problems !!