Leveling Kit?

[04z71steve]

hey guys, i'm kinda new to this site, and i'm looking for some suggestions i'm 19 and i have an 04 z71, i was thinking about going to the dealership and having the leveling kit put on and having a shop install somewhere around a 1200lb to 2000lb helper spring in the rear, because we have a 18' tracker deep v, and a 25' see ray and the truck doesnt sag obviously because it has the offset with the lowered front end but if i get it up in the air its obvious that the back will drop so thats why i'm gonna have the helpers installed or possibley a bag system, but if you've used the leveling kit or had one installed just give me some of your experiences with it! your info would be greatly appreciated !!