One other primary variation is that the Stage 1 kit comes with one 92mm GT500 throttle overall body, when the Stage 2 package comes with the billet 112mm spherical throttle overall body (which takes advantage of GT500 electronics) that we reviewed before. *Reductions on parts from your company or aftermarket. https://kylerzvrmg.topbloghub.com/30879060/the-2014-ford-mustang-gt-whipple-diaries