If you are using a factory harness and are after an easy ECU upgrade, take a look at Haltech Plug'n'Play Adaptor Kits. These adaptors plug directly into your Haltech ECU and have a set of factory connectors on the other side which plug straight into the factory harness.
Features
Simple Haltech Plug'n'Play product that allows you to be up and running in just a few hours.
Quick start guide will walk you through installation of the Haltech Plug'n'Play adaptor into your vehicle.
Guide is accompanied by the full ECU manual and Software located on the CD or USB key provided with the ECU to refer to while completing your installation and configuration.