Spark Plugs - '57-'78 XL SHIRTS_RAMJETRACING Dyna testing has shown up

Dyna testing has shown up to a 3hp increase after installing the upgrade filter  on factory displacement M8 engines

Gasket & Mounting Hardware

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Don't fall for the cheap and flimsy knock offs

Manufacturer Part Number: MK687SBK

Spark Plugs - '57-'78 XL SHIRTS_RAMJETRACING Dyna testing has shown upPlugs have a unique look with their black ceramic body and bold red logo script Insulator is made of 95% pure alumina; features strong resistance to heat shock and superior insulation Multi rib design of insulator eliminates flashover Nickel plated housing prevents oxidation and corrosion Multilayer gaskets and heat crimping process ensure a leak free, gas tight fit Copper core electrode prevents oxidation and corrosion and has good electrical and