Don't mess with it. I tried one and it didn't work out in my favor. Let just put it this way. It's old tech and alot of tuners don't support it anymore.
Now I will say, getting a tune is SOOO worth it. I know it's hard to justify the cost, but man it made such a huge difference. I gained so much low end TQ that it became dangerous to drive in the rain. It makes you wonder why ford didn't make the car like this before.