those are called torsion bars, they are the stock suspension of that truck, the skyjacker 4" suspension lift moves those mounting points lower off of the frame, which is why they look like big boxes, but they are stock(ish)
as for the tires, those look to me like 33's 31's (stock on the newer fx4's) look minuscule, even on a truck with only the 3"BL (trust me, that's what's on my truck right now) the 7" of lift makes any tire look smaller... those are 33 or bigger it's an edge model, so the stock for them i think were 28 or 30? it also looks like it's got blisten shocks on the rear...
as for the value of the mods, agreed, 10,000$ worth of work on a $5000 vehicle does not make it a 15,000$ vehicle, it makes it a $5000 vehicle with other stuff on it