Top off your Ford or GM Ignition system with these great new replacement coils. The blaster TFI and GM coils have MSD performance in factory style housings! MSD designed these coils by combining our blaster coil experience with E-core coil efficiency. Each coil has a unique turns ratio plus there is lower primary resistance than the stock coil. This all amounts to a bolt-in replacement coil that produces more output voltage. The coils will work with stock ignition systems as well as MSD equipped cars and trucks.