I know where you can get a good deal on a Nismo catback. *cough* *cough*
370Z Nismo Catback Exhaust
Honestly, I love the looks of it, fitment, etc. I even enjoy the sound (although it sounded much more to my liking when fitted with the HFC's) however I am selling it because I personally want something a bit louder and more aftermarket sounding. I purchase exhaust for sound/asthetics moreso than power gains. In that respect I think it's a little "tame" meaning I want something that will turn a few heads. The Nismo looks great, but it's only slightly louder than stock. Maybe that's what you're looking for? If so, like I said mine is for sale. Barely used, all original hardware and packaging.