Coil voltage

The E core is the best to use & easiest to wire in because the bal res is eliminated.
However people get sucked in with high voltage claims. 48000v is more than enough for a NA engine. Engine will actually only require 15-30KV to fire the plugs, the rest is in reserve. All else being equal, a 48Kv coil will have a more heat in the spark [ current ] & it is the heat, not the voltage, that ignites the mixture.