Were they gapped by someone? Because you're not supposed to gap them, you buy what you need (gap and heat range) and check them. You can gap them but you need to be very, very careful or they break, easily. I've ran Iridium in turbo cars (where gap is critical) and you can tell when they are going bad with hard misses (spark blow out) under boost. I've ran NGK, Autolite and Denso with good results. They last 25k-30k under turbo engine conditions.