[rotorwrench]

It would give redundancy for boats or aircraft. If one system quits the other is still working. On aircraft, it actually does make a tiny bit of difference in power but they have hemispherical chambers too. Elco heads and a few others were popular for hydroplane racing back in the day.

The mags are checked for proper drop off in rpm prior to each flight. Normal drop off in rpm is 150 to 200 rpm at 2000 to 2500 rpm engine speed depending on normal operating rpm of each engine.