Good for you But you claimed the DL50 iginition can die feeding it over 4.8v which is incorrect. The ignition module of the DL is an RC-EXL v2 that works fine up to 7 volts so also on an unregulated 2S A123 6.6v <u>if you keep the rpm below 8000</u>. The manufacturer however recommends using a diode which I did. Either the 400x or 500x series is fine and brings the voltage down to 5.8-6v depending on the load/rpm.

4.8v input voltage gives an output voltage of 12kV
6v in, 14.1kV out
7v in, 16kV out.

So yes, a higher voltages gives a hotter spark.