I have the same TB on my car......except it came from Ford Racing. Basically, it is a factory 70mm off of a 5.4L (should have "5.4" cast into the housing somewhere). It looks like all they did was over-bore it from the back side and install a larger throttle plate. There's a small shoulder about an inch in front of the throttle plate where they stopped the bore.
I was disappointed when I first saw it, but I've ran it for several years and it works great....and it's OEM quality. As for performance, I did notice a difference in throttle modulation and it seems to rev better on the top end. Realistically, you won't notice much difference with any brand of TB, especially on a stock to mild engine or if you still have the factory plenum. I'm sure a good aftermarket 70mm unit would flow better, but if you don't need it, it doesn't matter much. Go ahead and install it, it will be a slight improvement. If it makes you feel better, remember that Ford sells the same unit as a performance upgrade.