Throttle response isn't all it's cracked up to be. My car's response is very fast, 70mm TB and 12# flywheel. If I think of touching the peddle it revs to 3k. Trying to hold a low rpm is tough.
Other thing is I can't feel any gains after 1/2 throttle. That's because it's the point where the pressure drop to the manifold is already equal to atmospheric.
I honestly like a smaller TB better. I get more feel vs peddle travel. If I push it to WOT, it feels like WOT.
So I'm going to say to save the money you'd spend on the TB for the tuner/tune. It will benefit you more in the end.
Other things are full exhaust, cams, Lentec, raise compression ...
There are points where you'll need a larger TB. But 70% of the site is not at that point, not even me. Stock can flow lots of air. It's just one of those parts you replace because you can. Doesn't really do much for the car though.
13 years, 124,000 members and still no sponsored racing.