ACCEL spark plugs are engineered to create a considerably hotter spark that lets the flame expand more rapidly in the combustion chamber and creates a more complete and efficient burn of the air/fuel mixture. They build significantly more power at high rpm, reduce fouling and misfire, minimize flame dissipation, and give you instant throttle response and noticeably better fuel economy. Redesigned to reflect advancements in cylinder head and fuel management technology, these copper-core plugs with conventional ground electrodes also provide increased thermal conductivity and come with machine-rolled 14mm threads to protect your cylinder heads.