[SaleenCobra425]

Just as vidmaster said, use your GT harnesses and computer. I have done a ton of research on the subject. Years ago (~2005), everyone was saying to use a Cobra harness. I started a 5.4L DOHC swap into a 2001 Mustang GT in 2007 and bought a Cobra harness. Shortly there after, I sold the Cobra harness. On one of my computers, I have the two wiring pin outs for the different cars (01 Cobra & 01 GT) and they are very different, far from "plug & play". My best advice to you is this, as you are taking the 2V out, label all your connectors. Then, disconnect the GT engine harness from the car (bolt on connector in rear of engine bay on passenger side). Pop your 4V in the engine bay with ALL the sensors in place. Start laying your GT harness over the motor and see what does not match up. The COP wires are going to have to come out of the fuel injector wire loom and get their own created. As stated earlier, the polarity will also have to be swapped. Some of the other stuff will have to be lengthened or pulled out of its loom and re wrapped. The whole wiring job, in my book anyways, could be completed in less than 8 hours from start to finish if everything is properly labeled. That time includes cutting all your loom apart, stringing everything out, lengthening the wires you need to and re looming. I struggled with the project for months trying to figure out the wiring and what you read above is my first hand experience. Let all my stress save you some.
-Kyle