I think the thought was to run open headers vs the X-pipe? The difference between 3" and 3.5" back to the mufflers is less than 2 lbs. A 3" X with 3" mufflers from the headers is around 35lbs total.
Just as an fyi, a full 3" kit from the headers; X, midpipes, mufflers, tailpipes, 4 big hangers, 10 heavy duty U clamps, packaging and the box it ships in is 70lbs.