If following M. B. DOCs advice, then a properly gapped spark plug would in essence run better when it was worn out to .040". Of course the plugs do work better when new due to a sharp center electrode edge rather than a worn out rounded edge. I would still recommend a proper gap, the surrounding molecules will be involved in the burn "in due time". This may be a better way to ignite the fuel as it can create a longer sustained burn and actually help smoother running and more power.The electrical system was designed with a predetermined air gap, and I feel it is best to stick with it. Modular vee engines and I believe the updated 111 "EVO" motor use 1 mm air gap. Some of the "hybrid" FSS cars used Bosch F8KTCR plugs, which are dual ground lug plugs and were not supposed to be adjusted, unsure if there is a listed gap spec or not. I've found the normal Bosch plugs to be a little on the wide side when new, all plugs with a service spec on the gap should be inspected and regapped if neccesary as a matter of course. The plugs may be used for applications with varying gaps, so i'm sure Bosch (or any other manufacturer) doesn't really sweat what the gap ends up being as long as it's close. No disrespect intended towards M.B. DOC, thought I would give my view on this.....