I'll be blown away if they make a Twin Turbo engine in production. What ever the displacment is. If the car actully goes into production, we'll most likely see the VQ35, or maybe a bored out VQ, but no TT. It'll cost too much, and no way Nissan can make money on it.
You can all point and laugh if it does come with a 450HP motor. In which case I'll take my punishment, and accept the financial penilty of owning one.