Originally Posted by Cyber370

Firstly, what engine oil (viscosity and type) are you using. If you don’t know then change it immediately to a good 5W30 synthetic. The engine’s VVET system is known to make slight rattling noise. Good synthetic oil should help. Or you can try the Nissan Ester oil which was specially developed for our engine to reduce the noise that the VVET can make.

Second thing that can rattle is the clutch. Try revving with the clutch depressed. If it goes away, then it’s the clutch and you’ll either learn to live with it or change it.

I would start with that. By the way, both of those items are no cause for alarm. They’re just annoyances you get from a high performance car with little to no sound proofing.