Is it that good?
anyway this guys from the edmunds.com made a comparisson btwn the turbo and the GT... and this is the conclusion (at least they start to say that "the Nissan is almost as fast" as the 911 and no faster as so many where saying):
The Best of the Best
For all-round ability, I have no doubt the Nissan is the best car I've ever driven. It is almost as fast as the Porsche - which means it's almost as fast as any car on earth - and inspires more confidence through corners, yet it's also more roomy and practical and has a proper modern gearbox. It's a big, solid car you can rely on when the going gets tricky, that you can thrash around a track, then set the suspension to soft, the transmission to auto, the Bose audio to full bass and putter into town without a trace of angst.
Oh, I nearly forgot - price. The 911 Turbo comes in at about $100,000, which is a good value for such a stupendous car, but the GT-R will cost about $40,000 less.
Mizuno-san is right. This car has no competitors. Not at any price. But that won't prevent one of the first GT-Rs in Europe from being bought by an anonymous man and taken to Porsche AG in Stuttgart for a thorough examination. With an even more powerful and lighter V-Spec GT-R on the way, Porsche can't afford to lag behind for long.
and the link: http://www.edmunds.com/insideline/do/Features/articleId=123940#8
hope it is not a repost