Non Big Tow Titans come with 2.94 gears, while BT Titans come with 3.36 gears.
If you swap between the two, UpRev can make the necessary changes in your ECU. You will also retain cruise control.
Anything other gears and you'll lose cruise control.
With that being said, some of the fastest Titans use the 2.94 gears. I prefer the 3.36, just because it has a little more SOTP feel driving around town, but I doubt it would be any faster at the track.