[53lowdown]

At stock ride height the track bar is running pretty much level. The more you lower your truck, the track bar angles more which pulls the rear axle to the driver-side, which would cause your truck to 'dog walk' down the road.
My truck was lowered 5 inches with stock trackbar and it wasn't that noticeable, but when I lowered it another 2 inches I put in an adjustable track bar to keep the rear axle centered.
You might be ok with only a 4 inch drop and stock track bar.