Sure does look dirty. Are you running a tune device that would benefit from 93+ octane? If not why use it? Probably placebo effect at best.I had my stock plugs replaced with a set of NGK (1422) ILKR8E6 and noticed the originals looked pretty dirty with carbon buildup. There is only 9K on them, perhaps this is normal or the stock ones were crap. Also, I used a few brands of octane booster which could be the culprit. Any thought anyone has, please share.