I'm going to change so quick

[shootingstar]

.....
George: I'm celebrating because I've got a friend who tells me all the things that ought to be told me.
Emily: George, please don't think of that. I don't know why I said it. it's not true. You're -
George: No, Emily, you stick to it. I'm glad you spoke to me like you did. But you'll see: I'm going to change so quick - you bet I'm going to change. And Emily, I want to ask you a favor.
Emily: What?
.....
(Thornton Wilder, Our Town, Act II)

I've an issue with the word "so". What does "so" express here and which word does it belong to? Does it belong to change - as an object representing "it", referring to what Emily has said before, or does it belong to quick - to emphasize quick? I think "so" refers to what Emely has complained of shortly before - it's an object.
(Note: I know why George doesn't say quickly actually)

 

[emsr2d2]

It emphasises "quick". It's used in the same way as "very" or "extremely" (a usage we tend to discourage learners from using). For me, there's an implied result:
I'm going to change so quick that you won't believe it!

 

[Barque]

In speech, we often stop in the middle of a sentence and start another one. That probably happens in every language; it's how we all speak. George probably meant "I'm going to change so quick that you won't believe it" and changed his mind midway through. Wilder was trying to mimic real life speech by that line.

(Note: I know why George doesn't say quickly actually)

Do you mean "I don't know..."?

"Quick" is often used to mean "quickly" in AmE, which is what George speaks.