On my previous 350z before boosting.
Berk decats, Stillen Y-pipe back to a Scorpion backbox, quieter than say the outlandish Cobra backbox and a lot nicer looking imho. Sounded gorgeous on full chat with a pop and bang map from Abbey.
Don't forget with the 350z, for the small amount of things you can 'bolt on', you will get zero gains unless you get an Uprev. The ECU within a few miles of driving will simply dial out any changes it detects back to standard parameters...
So if you're also chasing numbers get all your changes done first, then go for an Uprev to save yourself some money tweaking the map each time.
Honestly your best bet is to just jump on Youtube and have a listen, I'm sure someone somewhere has strapped on everything under the sun to these cars, you need to make sure you like the noise it makes
Don't forget the actual 350z forum
https://www.350z-uk.com. Much like here you'll have people on there with a wealth of knowledge to help you and I've no doubt the topic has probably been covered somewhere in the archives