Pulled the engine harness and ecu. There were only 3 wires merged from Miata harness - red, yellow/black, and blue/red.

I want to replace some wires. Problem is 1. finding right colors and 2. How to replace the entire wire from ecu > pigtail etc.

This article is helpful. http://www.popularmechanics.com/cars/how-to/a643/2705606/