Is the Nissan Skyline street legal in USA?

A stock Nissan Skyline (I'm uming GT-R, in Japan a Nissan Skyline can be any number of cars) is illegal to register/drive in the United States. This is due to a number of factors, such as not being compliant with federal emissions standards and crash tests (not the same as killing too many people). Several companies modify Skyline GT-Rs, the most well-known being Motorex (a href="http://www.motorex.net/motorex.html" rel="nofollow"http://www.motorex.net/motorex.html/a for more information). However, this can become prohibitively expensive, to the point where you can get better performance for less in an already US-Legal car such as a new Subaru WRX STi or Mitsubishi Lancer Evolution.