My 4-link weighs way way less than the leafs it replaced, but i put on a heavy lid, lineX, and carpet kit so i'm still overweight back there. I'd probably drop a half second just removing that heavy lid, in the 1/8th i lose about .4 from only 130lbs, so I can imagine what 200+lbs is doing to me in the 1/4.

Also, the trailblazer EXT has an all aluminum 5.3 if you wanted to just replace your engine but save weight.