Every article that I have reviewed does not recommend going to the bigger t-bod-plenum until you do some decent mods to the 4.6, otherwise a loss of low-end power ends up as a result.
I.E full exhaust, CAI, boost, heads/cams.
I belmouthed my stock throttlebody as I don't plan on doing much else to my 04.
Also, an accufab 70 will flow better than a Ford 70mm t-body; FYI.
I was very happy with my Accufab 70mm TB and Accufab plenum on my basically stock (at the time) 02 GT. It really woke up the engine above 3000 RPMs - it was a noticeable difference. That said, it was an expensive upgrade. But I wouldn't bother with any other throttle body, and their plenum is top notch too. Would I do it again? Probably not...as said, it was expensive.
I'd do many other upgrades before that (exhaust, gears, shifter, suspension)...and I'd save for a supercharger if I was doing it all over again.