I find myself being a bit skeptical that will make a detectable difference.
Maybe something (a little) at full throttle, but not otherwise.
And, I suspect it's not so much the bore diameter increase that would make a flow increase, but the reduction of the step change in tube diameter at the inlet, where the soft tube coming in fits over the outside diameter. That step change in diameter creates turbulence, and so some minor pressure drop there. A low angle bevel at the throttle body inlet, while keeping the bore diameter the same, might be just as effective. The throttle body outlet already matches the intake manifold inlet, I think, so nothing to be gained there by a bore increase. Might even loose something by adding another step change there, unless the gasket and manifold was also opened up to match.
The throttle plate axle shaft also is a small turbulence / pressure drop point when fully open. But fixing that would require an elaborate machined throttle plate to smooth the flow. Expensive for such a small benefit.
And besides, the entire point of the throttle plate being there in the first place, is to create a variable pressure drop (mass flow reduction) at all throttle positions less than full.
Any flow increase would be adjusted for, closed loop, by closing the throttle a little, so...no point?
