There really is nothing that you can get that will make it sound similar to the old G35. I had a 03 G35 and that engine sound was unique and the 3.7 liter versions dont replicate the sound and it actually creates more hissing with aftermarket exhausts. I only talk about the drone and loudness getting old fast because I went from stock, to a Fujitsubo, to a custom single with a HKS carbon "muffler". It wasnt really a muffler other than a resonator with baffles on the inside. Had to run the exhaust with the "cap" installed most of the time due to noise and interior drone.
Chances are you will have to bring it in from the mainland...almost positive on that one. The ones that seem to be having a good review and response is the Fast Intentions version. I had a Fujitsubo on my G35 and I really liked that sound too. You could opt for the Amuse version too though.
One thing that I did notice was American exhausts seem to focus more on the lower tones while JDM versions tend to make it more European sounding....leaning towards the higher pitched......Ferrari like...sorta sound, if that makes any sense. But that is just in my opinion.
