I had a very random misfire. Some days it'll work perfect, others it'll go into boxer mode. This happened very randomly, no set amount of boost or revs could get it to trigger. I had UAS and Grey Imports both look at my coils but they both reported them to be fine. I finally got it to misfire when I had the car at Grey Imports. Coil pack #1 was the culprit. Replaced that and all is good now, but I'm saving up for some Spitfires now.