vtc...
'The VTC system varies the intake valve opening and closing time by managing the cam phase. The system is driven by oil pressure controlled by the VTC solenoid. As well as maximising useable power and torque when required, the VTC system contributes to improved engine idling stability and lowered fuel consumption'
From
http://www.4wdworld.com.au/releases/nissan.htm
No need for an aftermarket adjustable sprocket
Nissan already built it in!!
Thanks for the correction wes