If you`re running high boost (15+ psi), these are the plugs to have. They don`t have an internal resistor so 100% of the spark energy goes into the arc. We`ve seen these solve high-boost misfire problems on 400 hp cars. You`ll be able to run a bigger gap, which means a bigger spark and more power. It`s the cheapest ignition upgrade you can get.
NGK R5671A-7
$15 shipped
NGK R5671A-7
$15 shipped