I just wanted to shine some light on this subject by measuring both holes; t-body and intake and this is what i got:
Intake Entry Hole Size:
Throttle Body Size:
So, the conclusion is when you have a 63mm Intake Manifold entry hole size and you install a 65, 68, 256mm throttle body on it, it wont really give you any more air into the manifold, because the manifold is still 63mm!!
Save your money and time, it's just another way for those companies to make that extra dollar.