DeutschTuning proudly offers HKS SUPER FIRE One Step Colder Spark Plug (heat range 9) for Mercedes AMG M177 and M178 C63/GLC63/C63S/GLC63S/E63S/GT63S. This is our go-to spark plug choice for our stage 2 and up AMG vehicles. We highly recommend these spark plugs for their durability and higher tolerance for tuned AMG M177 and M178 engines. Comes as a set of 8 and we recommend gapping to .024-.026. Please contact us with any fitment or item questions.