I'm sure I saw one pop up on the forum the other week.
IMO, search for another exhaust. There isn't anything wrong with them, but they're a bit old now. I'm pretty sure these were some of the earlier aftermarket exhausts made for the Zed.
IIRC it can be raspy. With the design of it (2 Cans, no back box) It's going to be loud/droney with decats.
I wouldn't pay more than £200 for Backbox/Mid pipe.
On a brighter note, I have an entire exhaust system up for sale
http://www.350z-uk.com/topic/101326-for-sale-full-custom-exhaust-system-inc-decatsy-pipe/
No drone, Nice tone, loud when you want it, and will get accepted on most tracks