You need to figure out exactly what you want to do first. There are so many variables when it comes to modding these trucks that we cant offer any suggestions until you give us more info. Doing some reading of build threads or searching for threads about tuners/exhaust/liftpumps will give you ample time and info in order to ask informed questions....
I have a 2005 lly that is bone stock just trying to get ideas what kinds of mods to get? Help!! Please