Before you spend cash on an intake, you should check out the link below. Some Dyno testing from Cobb Tuning on various intakes for the VQ35HR and VQ37HR.They test the Fujita, Nismo, the factory set-up, and a few others.
Seems like some K&N Drop-ins are all that's needed, if that.
http://blogs.cobbtuning.com/?p=160