Pete,
I set up an MS system on an RB25DET for a friend, and I used the stock COP coils, controlled by six VB921 chips. The stock COP coils have a three wire connector interface and do not contain anything more than the boring old coils of wire wrapped around an iron core assembly. The factory wiring diagram for the motor I modified shows an external ignitor box used to fire the coils, and that ignitor was certainly in my hands when I cut the wires off it's connector. I hated cutting perfectly good parts off, but it was done in the interest of neatness because the ignitor usually sits at the back end of the valve cover (and apparently "it looks ugly"). The COP coil primary connections are as follows:
* primary supply
* primary "ground" (I use the term "ground" loosely in this case)
* secondary ground
All six of the secondary grounds are tied together in the COP sub-harness, and terminate at a ring terminal attached to one of the bolts retaining the coil cage to the head. Seems rather stupid to separate the grounds, then tie them all together a few inches away, but I'd be the last one to question the reasons for it because I was able to make the motor work fine using that sub-harness.
All six of the primary powers are tied together as well. The six primary low-side terminals (primary "ground" for each coil) are separated as you'd expect.
Cylinder 1 (output1) = B/R
Cylinder 5 (output2) = R/Y
Cylinder 3 (output3) = R
Cylinder 6 (output4) = R/L
Cylinder 2 (output5) = R/W
Cylinder 4 (output6) = R/G
+12V Power Supply = W
IGN Coil Ground (A-69) = B
There is also a remote-mounted condensor capacitor on the stock ignition setup. It was quite small, and I had a spare 100uF 400V capacitor lying around so for good measure, I threw that big capacitor into my wiring, connected as close to the coils as electrically possible.
All of that gibberish aside, I know there are at least two styles of coils used on the RB25DET motors, and both of the two COP coils I've had in my hands have used a similar three pin primary connector. I wouldn't be at all surprised if the later RB25 NEO engine use some COP assembly with internally-integrated electronic controls, as this seems to be the way most companies went in that era.
I see that Delphi are now making COP coils with integrated ion-sensing mechanisms. I can't wait for the trickle-down of that technology!