I just did mine today. Out of the box, the plugs were .035. I used a wire gauge and gapped them .044.
Car runs fine.
Copied from NGK's site; "5 things you need to know about spark plugs".
3. Gapping fine-wire spark plugs
In the late 1980s, when fine-wire spark plugs first appeared, installers used incorrect gap tools and procedures resulting in bent or broken-off firing electrodes. As a result, many people assumed that one cannot adjust the gap on a precious metal plug. While most NGK spark plugs are pre-gapped, there are instances where the gap requires modification. NGK recommends a wire-style or feeler gage gap tool, which can adjust the gap without prying against the center electrode. NGK also recommends adjusting the gap no more than +/- 0.008” from the preset gap.
There's an NGK video on it too.
I did mine very carefully under a magnifying glass to be sure.
Get yourself one of those desktop lighted magnifying lights.
When using the wire gauge;
>You may have to buy two tools to get an assortment of wire sizes.
>Rest your hands on a steady surface.
>Hold the tool in your fingertips.
>Be sure to hold it perfectly parallel to the electrode otherwise you will get an incorrect measurement.
>Don't FORCE the tool into the gap. Start low and work your way up. PRACTICE on old plugs.
>Use several wires to approximate your measurement.
>If the wire JUST slides past the electrode don't yank it out. Open the gap a .001 or so with a second tool, then remove the first.
FYI, I run/ran Iridium plugs in my Honda dirt bikes for years and we always gapped them too.