These are a great plug, that I got lots of miles on, even in what I would consider to be extreme conditions.I bought 6 of these to replace the plugs in my 2001 Audi S4.I had been running a AWE Tuning Stage III tune (K04 Turbos, green top injectors, upgraded MAF housing, and a stage III chip) At the time I had the car out in the desert of southern california, which is just about the worst environment you could imagine for a performance car. 91 octane at best, with 15% ethanol, 100+ degree temps, sand, and no moisture. With my stock intercolers, my intake temps at idle were frequently 65 degrees celsius.Anyways, the plugs persevered through all that, getting me 4 solid years of use before I replaced them, in Ohio, when cold starting resulting in rocky idle. Replacing them cured the rocky idle, but didn't clear up the rough motor when I would first pull away. As such, I've determined that my problem wasn't the plugs so much as the miles on the car...