From what I've heard is on the GTO2 some already come with the pipes unlocked, so you may not have to do any flashing. But if you do have to flash it is not that hard, just google it. Trust me I flashed my card and had no clue about it before. So I will suggest to you the GTO2 because when all pipes are unlocked it offers better performance.
BTW, to check if all pipes are unlocked just dl ATItool.
GL.