My buddy has an '03 G35 Coupe. Very nice car, interior is sweet except for the fake aluminum plastic trim that scratches easily. No balls down low, but pulls nicely up top.
The Mustang is too retro. If I wanted a '67 Mustang, I'd go out and get one. But I think it's V8 will have more potential, and any Cobra version would kick the G35's ass unless the Skyline version of the G35 ever makes it to the States.
My vote.....G35.
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What is best in life?
"To crush your enemies, see them driven before you, and to hear the lamentation of the women!" -Conan