In any event I found something on DigiKey that will work well.
12 wires 22 gage solid color coded in a vinyl jacket.  I can sell this for a
buck fifty  cash a foot 10 foot minimum plus $5 flat rate mailing to all you
people wiring the EC2 and the EC3. This will be the EC to PCM harness only.
It is larger than the RS232 cable so it is easier to work with.
This is a favor. I am not getting rich let alone a profit. It is
just that I have to buy 100 feet. When that is gone it is gone.

All the rest of the harnesses can be made up from single strands in a
split jacket.

I am working on a break out PC board from the EC2 37 pin
D sub min that will group all the wires together neatly for each harness.
It will also pickup the ground stud. It will have cable or jacket
strain relief for each harness. It lies flat parallel with
the top cover of the EC2 and is smaller than the off the shelf
break out boards shown in this jpg. I am not happy with
the wires going in all directions at the same time as shown.

Paul Lamar

I added a couple of bus bars on top of the engine to handle
the injector and coil wiring. Four switched 12 volt wires
for the the injectors and four for the coils.
The RX8 coils also have four ground wires.
The RX8 coils are not wired yet.

The injectors are grounded by Tracy's computer to squirt
so fairly heavy wire is needed to run back to the computer.
Surge current can be a couple of amps. This picture shows
the injectors half wired.  The red wire indicates it is
12 volts. A black wire is for ground.

A large 100 mfd  50 volt capacitor connected
between the switched bus  and the ground bus is a good
idea to handle the surge currents.

These bus bars are SS boat units about $10 each.
Most of the sensor grounds go to ground bus as well.
Same for the alternator ground. The alternator field
coil 12 volts can come off the switched 12 volts bus
as well. Not connected yet.

This makes for a simple system that is straight forward,
easy to understand, easy to trouble shoot and easy to fix.

Paul Lamar