Teach me Pls "Tune"

Hi everybody, I got my first stang (V6 Auto, Candy apple Convertible) I a'm comming from the miata word, but want a car who can serve me well and give me some space "Miata Suck for that". I choose the stang, very different car deserving différent need ! but still convertible.

I read on some post saying about a "tune" can make the auto transmission perfom better. I a'm not searching for more HP, or make someting to redicaly decrease millage performance , but i find the transmision is a bit on the slow side to react .... A more sporty shifting spririts could be very appreciated.

Anyway... teach me pls.

A tune, is a kind of sofware upgrade ?
Can I do it myself, do i need a shop ?
Wat is the cost of it ?
Do I need to have other mod, Can I make a tune on a stock car and expect result ?
What happen with the Garantie ?
Do I miss someting ?

* Sorry for my english... I'm born with the french "Tune" version

Tank you in advance !!

Thank's all,

I guess TheVat u are right, the day I will have some trouble that will be the easyest way for ford to walk away....

Do we have some owner here who did the tune upgrate only for wake up the transmission, what should i expect ?? different shiftpoint and firmess on paper sound good but on a day to day drive, what your impression ?

Whort it ? or not