Don't know what a 2015 ss weighs, non 1le, but the 1le that motor trend tested was only like 80lbs heavier than the loaded mustang. I'm assuming it'll be 100lbs lighter than a comparable gt. Ford left a ton of room for upgraded suspension and tires on the gt pp, as you know. I expect the 17 to have revised power, suspension and maybe better tires on the pp.