• 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.
• More Durability and a Higher Melting Point Than Platinum
• Better Center Electrode Anti-Oxidation and Anti-Erosion.
• Improved Ignition and less strain is placed on the ignition system.
• Superior Anti-Fouling.
• Better fuel economy, increased power/acceleration and especially better throttle response.

It may be time to invest in some precious metal.