When I had Brazel's do my Ford V10...
First, we talked on the phone about what I had, how it performed, and what I'd like him to change.
Then he sent me the programmer, with instructions to hook it up, upload my current tune, and another thing or two. My understanding is the unit is "married" to one particular Ford ECM.
And then I sent the tuner back to him.
Got it back in a week, with a trial tune on it.
I flashed my ECM and drove for a while.
Called Jon, told him this and that are good, this and this other thing needs a little more tweaking, he emailed me a new tune. 3 times before I was happy.
When done, that was the best running 99 pace arrow on the continent.
I traded it in with the ultrapower tuner connected and sitting on the dash, and I'm sure whoever bought it from lazydays was very happy with it.
It was not under warrantee at any time during my ownership, not sure who brought up warrantee, it was neither me nor the OP.
and again, we're not talking about making it breath fire here or anything. Overall smoothness, throttle response, and especially getting the transmission shifting under control, that was the biggest difference.
Accellerating, pedal to the metal, down an onramp, there was no difference at all.
Cruising down a highway, up and down mild hills, huge difference.