These fantastic new replacement coils will complete your Ford or GM ignition system. The MSD Performance coils for the blaster TFI and GM have factory-style housings. By fusing the effectiveness of core coils with our expertise with blaster coils, MSD created these coils. Every coil has a different turns ratio, and the main resistance is lower than it is with the standard coil. All of this adds up to a bolt-in substitute coil with a higher output voltage. The coils are compatible with both original ignition systems and vehicles outfitted with MSD. Use a PN 8874 harness for a straight plug-in assembly if you intend to add an MSD Ignition with your blaster TFI coil. Use a PN 8876 connector for the blasting GM coil. Also