For racing-CDI units got to:
The Takegawa Hyper CDI-unit is a cheap ($50) racing CDI with a good performance. These three manufacturers also have highly tuned CDI-units, but those cost a lot.
These CDI-units are originally made for a Honda 4-stroke, they might not work propperly on a 2-stroke. I think you'd best try your local moped-dealer first.