Its the whole design. Dual clutch for faster shifts. The dct gearing for faster accel. The launch control too.
Then you go into aero and the Chassis design (weight evened out over each axel (engine and trans over each axel)). See press kit but this matched with the aero reduces drag. Weight also has an affect on the aero/chassis (from interviews).
Look at a dyno graph to see its characteristics for acceleration iirc torque starts low and keeps up.
There is a lot more but that's the basics iirc.
Check out the gtr press kit which will detail more.