DENSO Iridium Power® spark plugs represent a performance breakthrough. IRIDIUM POWER best demonstrates its performance improvement during acceleration. IRIDIUM POWER has a 0.4 mm diameter iridium center electrode - the slimmest iridium electrode in the industry - and a specially shaped ground electrode. These features combine to achieve higher ignitability and require lower spark voltage than ever before. This enables high-response driving with fewer misfires than under higher required voltage spark conditions and fewer misfires when ignitability is difficult. As a result, acceleration improves in comparison with normal plugs.

The power produced by the 0.4mm dia. iridium center electrode is IRIDIUM POWER unmatched by other plugs. Using a 0.4mm dia. fine center electrode, there is more power compared to 0.8mm and 2.5mm dia. plugs. This is what makes the difference in acceleration and in your lap time.


NGK produce Iridium spark plugs, product range known as Iridium IX designed specifically for the performance enthusiast. Iridium IX® offers extreme ignitability, improved throttle response and superior anti fouling. Benefits of improved ignition/combustion include better fuel economy, increased power/acceleration and especially better throttle response. These NGK Iridium IX spark plugs feature an ultra-fine center electrode that's designed just thick enough to ensure the maximum durability and life of the spark plugs, and just thin enough to create an accurate and consistent spark.

They represent the ultimate evolution of spark plug technology and performance. Iridium is significantly stronger than any metal used in spark plugs today. It's the hardest metal used (in fact, iridium is 6 times harder than platinum), which has allowed NGK engineers to reduce the voltage requirement for a spark.

NGK Iridium IX types have a centre electrode tipped with Iridium alloy with a 0.6mm diameter. NGK believe this gives the optimum balance between performance and service life. Service life estimates can be up to 60000 miles for normally aspirated car engines and up to 20000 miles for motorcycles - this is extremely subjective though, a high revving motorcycle or extremely modified car engine will most likely wear plugs out in a few thousand miles.