I've had several inquiries about building an alternative solution to the Andial Splitter that's becoming very hard to source these days.
The good news is that after reviewing what's needed to fire the 964 twin coils from a 84-89 Carrera DME it turns out I found a better simpler approach that does not require you to splice into the DME harness near the DME (under the seat).
I've come up with a new tinny circuit module that can go into the engine bay, then all that's needed is to build a custom harness to mate up to the 964 coils, with coils mounted on the standard 964 coil bracket and the 2 ignitor modules mounted on the bracket. Basically you source these parts from a 964 exactly like in this picture:
Then I create the small circuit module and you can easily build this harness:
The entire solution then wires up in the engine bay with 4 simple wires! I added that 30amp relay to insure the 2 coils get powered from a solid 12v source, you could power the setup without the relay from the stock coil's '+' black wire but that wire is feed via the ignition switch. I felt that a relay was in order, so I added one. I actually advice getting main constant power for the relay from the starter, this way you have solid supply of 12v for both coils. The rear fuse block is also a decent source of power but may require a few small mods, I'll outline these mods soon when I post pictures of the setup fully installed in a test car.