i didn't see the part about the pietcard box.
i fried one of these a few years ago and cut it open, turns out the main power capacitor in there is rated 150v which is way less than the treat cdi is capable of putting out. the components are also sub-garbage.
they work fine when paired with a low-output Pietcard internal coil, but they are likely to get fried hooked up to a treats CDI. The 13 dollar 'scrappy dog scooters' Jog cdi works good with the Treat CDI, until the trigger coil burns out.
The treat CDI can be made to work, but woof, its a pain in the ass. Way better options out there. Sounds like you are on the right track. I have seen them break up at high rpms but they don't sound like that when they do... which isn't to say its not possible that is your problem, just saying, when i've had them go out, that is not what they sound like.
I would be running points on a setup like that, and certainly first thing i would try for trouble shooting is to go back to points to eliminate the variable.