I've got the Cortex 3950 for my 2007 4.7 and it so far has been a great tuner. Obviously not the most powerful engine these trucks have ever seen, but with the tuner I've put it on the 91 octane performance tune with 93 octane gas as well as gotten the transmission upgrade and set my shift points it honestly feels like a different truck. The gear shifting is so direct, it feels great. I've even gotten better gas mileage from having that tune, still a trucks gas mileage though. If you do go with a cortex and mess around with the shift points and torque conversion and whatnot, if you don't already know about it make sure you do your homework on it.
Also, completely off topic, you have a really good looking truck. Love the stance and the color. Is that a new body style tailgate on it?