the igniter does not increase spark voltage, it does increase the accersey of the spark timing, the coil is what increases spark voltage, more voltage the wider you can run plug gap, wider gap expoes the fuel charge to more spark flame so combustion is more complete, you can run.040 plug gap with a 40,000 volt coil ,wider if you run a hotter coil, i have a chevy v/8 with an hei dist which i used to replace the stock points dist, the engine idled 300 rpm more with the hei at the same timing advance, hotter and wider spark will increase engine performance, less hesitation on throttle changes