You will need an ext pipe. The car itself (the g coupe) is 8 inches longer than the 350z, you can buy the "ext pipe" off mynismo.com IF the diameter is the same, or have an exhaust shop fabricate you one, shouldn't be that much.
No problem it will fit without any issues (extension is needed) pipe size is 2.50" so any muffler shop that has any talent could install and make the extension for you. Magnaflow makes a nice single exhaust and you'll like the sound. Gary