Yeah, there seems to be some problem with the coil packs on EF's, regarding the voltage output, with a hot engine bay. I have tried Magnacore 8.8 Leads ($80 bucks), Split fire plugs ($16 EACH!!!), and standard NGK R Plugs for the XR6 (Cant remember the type). The magnacore leads made the most difference. The car before the lead change would stutter at 60kpmh, when flooring it, but with the lead change, and same plugs, the car went a lot better, The split fires made about as much improvement to the performance as the standrard NGK-R Plugs, and considering I can get 6 NGK's for the price of 1 splitfire, I will be replacing my plugs with NGK's from now on !!!