CDI Most reliable multi channel CDI The core of the system is the M&W Pro Drag 500 CDI ignition box.  This is the strongest and most reliable multi channel CDI on the market, supplying 320mJ in low power mode and 500mJ in high power mode.   Due to the fact that there is not a non resistor type spark plug available for the GTR, we use and recommend using this system in 320mJ mode, as it's more than enough spark for 450 hp per cylinder on methanol, and will not hurt the spark plugs.