RCPilot if you do a google search on CDI ignitions you will get many hits some of which have an explaination of how it works.
It seems strange to me that if you go to the compexity of putting an oscillator and a transformer in the primary circuit why not go all the way to say 6000 volts and dump the capicitor directly through the spark plug. That way you could eliminate the output coil. From what I read you only need about 5000 volts to fire the plug. If you are limited by the dielectric strength of the capacitor you could charge several in parallel and discharge them in series.
This has been an interesting thread but I think its gone a bit off the intent.