I had done a few head unit installs in my time on the tools and didnt look back fondly at those days where I had my head in a dash trying to wire up the unit. I am sure Im too old for that now. Then I saw someone point out wiring harnesses. Mazda to ISO then ISO to "brand"(in my case Alpine). These were about $20 each so that 2x$20 to do the job
Then I saw a Mazda to aftermarket harness for $15ish. Plugs directly in to the mazda plugs but was simply coloured wires coming out of the harness. These were colour coded and named in the same way most aftermarket head units colour code their wires. What this meant to me was that I could do a quality join (soldered and heat shrunk) on the work bench. I did this today and I must say that the connections would be 50% better than what I would have done inside the car and I could stand up while I was doing it.
I got my harness from http://myworld.ebay.com.au/original_car_stereos who I cannot speak more highly of for the 1 time I have dealt there. Aeropro part # AP7901F

So if you want to keep your original plug and are happy to do a bit of work, this is the go.
Stu