Besides the standard candles we can offer you special racing candles. They have a super fine iridium center electrode. Highly recommended for heavily tuned engines and when using internal rotor ignitions. The ignition spark is much more stable at high speeds, the fine electrodes clean better than conventional CU electrodes. You should use interference suppressed plugs if you have connected a rev counter, because without these suppressed plugs, rev counters sometimes react with extreme jumps in revs.