Jacob’s ignition testing. Thanks to Newbomb Turk….

What's the benefit of a hotter spark? Does it result in more horsepower?
Yes. It’s also a larger and more powerful spark. You can also open up the plug gap to make the spark longer. So you end up with a longer length hotter spark to more full ignite the fuel.

This results in more power (under full throttle or not) and mileage when cruising.