Upgraded fuel injectors for 2000-2006 tundra 2uz-fe

I think my 5vz T100 is going to need a set by the end of the year

 

I saw one reference to smoother shifting in this thread, and have seen reference to it in other places on the internet with respect to fuel injector replacement. Can anyone enlighten me on the mechanism that makes injector replacement equate to smoother shifting?

For context, I have an '05 with 204k miles on it that I have had since it was new. Taken well care of, got 17-18mpg originally and is now getting 14mpg regardless of how I drive. +2 tires and leveling kit, no roof racks, highway friendly traction tires. It also has some rough shifts occasionally. Just had the transmission fluid service at the dealer and they didn't indicate any signs of the transmission being worn out, for whatever that is worth (lol).

 

I believe it's due to the better fuel atomization allowing the engine to have a slightly wider power band, that in turn makes the trans hunt for gears less often. But I'm not sure