TOKYO — Honda is successfully campaigning its NSX coupe (Acura NSX in the U.S.) at the GT championship in Japan. Now it is translating the victories to street cred with the introduction of a special-edition model based on the GT racer. The NSX-R GT is guaranteed to be exclusive: Only five will be built and each will cost a cool half-million.Technically, there's not much difference from the normal NSX-R; it's powered by the same 280-horsepower, 3.2-liter V6. However, there are a few carbon-fiber parts, which guarantees better handling and makes the car look like a Transformer: a huge air intake behind the rear window in 1970s racer style, a front apron and an underbody diffuser.