GSR proven gains and hundreds of development hours spent finding the best location or Forge kit with no proven gains(that i know of) and made to look pretty. hmm hard choice.
i researched this a few months back....go for gsr..as matt said its proven, last time i checked forge were still testing to see how much gains came with their induction.....GSR is most common on here, and im sure anyone would say....GSR IS THE WAY TO GO