Coil On Plug Ignition (COP)These are the COPs used on in house engine builds running EFI. We selected these Denso coils because of their: 1. very high spark energy good enough for over 750whp on the Dynapack chassis dyno on an air cooled 911, and over 40psi boost on water cooled racing engines without blowing out the spark 2. excellent fit good seal to the valve covers, and low profile to make spark plug service in the car easy 3. extreme reliability unlike other manufacturer's