All depends on what you are towing. Unless you are going real big, the truck is probably fine just the way it is.
Check the weight ratings based on the trailer/5th wheel you are looking at to make sure you are within the ratings. Assuming you want to be legal and legit (some folks are happy exceeding the weight ratings but I won't tell you to do that), nothing should be needed if you are within the ratings.
By the way after market suspension equipement doesn't change the weight ratings of the truck.