what is different between the rev-up and non rev-up, is it a completely different engine?, or just improved parts?

is the 3.5 vq designed by nissan/infiniti, or did they buy the design/engine from renault, the french car maker?

what is the reason you need upraded plenum spacers?, ive been reading some threads but cant find out what is wrong with the standard spacers and what the hell does it? can someone explain the plenum theory please, i have an 04 at coupe(well, skyline 350gt really..) and i am looking to start the upgrades, thanks

 

You have a non rev-up. The Rev-up is a variation of your VQ35DE.

The VQ is a Nissan design.

Plenum spacers give the engine more air. More air = more power.

 

Plenum spacers change the length of runners minutely and the length from plenum to intake valve midpoint [half lift] sets the torque rpm reinforcent point. Also may change shape of flow at critical transition points.