My understanding of capacitive discharge ignition is that the muliplication of input voltage by an a fixed transformer ratio to get the output is not so.  Rather it is energy in joules that get transferred to create spark, and not simply voltage. </p>

The output voltage decays very rapidly.  The capacitor that dumps the charge also has an impedance that is rpm (frequency) dependent.  In other words, supplying a higher input voltage only provides a 'slightly' hotter spark.</p>