Don’t know if this helps but for the Focus Sigma engine I found information on the web that suggested the original gap specification was 1.25 to 1.35mm. This was then apparently reduced due to straining and failing the coil packs and 1.2mm is suggested. The original FoMoCo plugs that came out of my 4/4 were gapped at 1.2mm. NGK TR5B-13 are gapped at 1.3 out of the box and their suggested upgrade plug, LTR51X-11, is 1.1mm as the part numbers indicate. I fitted the upgrade Iridium’s straight out out of the box and they seem fine. Please don’t take this as gospel of course, usual disclaimer that you check this is correct etc.
