Pending Gear change, new tune needed?

[jumpn]

It's been forever since I've been on this site. Anyway, I can't recall if I will need a new tune for my 99 when I get 4.56 gears installed. If so, how long would the turn around time be for a tune to be written? I'm heading to Silver Lake Michigan for some sand dune wheeling, and want to make sure I'm getting the most out of it while running around on the beach.

I'm sure this has been discussed before, but I didn't see an answer that seemed to pertain to my situation.

thank you, Jumpn