Cdi/coil upgrades?

Not sure about a CDI upgrade but Nology makes and aftermarket coil & wire upgrade that works pretty good.
 
Whare can those be baught and what's the gains?

RJATV has them at good prices.
Theres a guy on E2S who 70hp KX500 gained a couple horses from the Nology coil and hot wire.
You can expect a snappier throttle response, faster starting, less fouling, better gas milage, and prolly a small hp gain.
I run the Nology coil and wire on my motor.