Here we have a set of 4 Denso Iridium Spark Plugs for your Evo 9. This plug is one step colder for those of you pushing more than 75 hp over stock. It uses the worlds smallest iridium elecrode that is a mere 0.4 mm in diameter. This makes for a more concentrated, electric potential at the electrode. Improves engine start up, driving and acceleration is improved.