If you use a 1.4 ohm coil, you need to leave the resistor wire in the system. But if the resistor wire is left in the system, the coil will only be seeing 6V supply, and will thus only be outputting 22.5k Volts.
The stock coil puts out around 18k volts, if I remember correctly, so you are not gaining much voltage to the plugs.
You ideally want one of the 3 ohm coils so that you can bypass the resistor wire and get the full 12V to the coil, thus getting the full 40-45k volts out of the coil.
http://www.amceaglenest.com/images/Downloads/MIU.pdf