You will be able to get good gains out of programmers. It will allow you to rmove rev limiters, remove top speed, change fuel ratio and mapping, change shift points and hardness, and a lot more. You can tune the vehicle yourself and get good gains from it but you will get the most out of it if you take the truck in with the programmer to a tuner at a dyno shop and have them do it. It can get expnsive but it is very much worth it.
From what ive heard the Jet Programmer is good but the SCT X3 tuner is the best. I am personally going to go with SCT X3 when I eventually get mine because more tuners are familiar with it, you can save multiple kinds of tunes, and its much easier to use. We used one on my dad's 2007 Mustang GT with a JLT Cold Air Intake and gained about 20 hp with both of them.