If it's an R33
You need to remove the entire dash trim that goes around the stereo/climate control, across the steering wheel.
Remove ash tray, 2 screws in there.
Remove trim around gear stick (just lift up at the drink holder end), 3 screws at bottom of trim under stereo.
The entire piece then clips off all the way to the right vent.
You need to pull it out far enough to fit a short screw driver in. The vent is a separate bit held on with 2 screws and a clip. It's pretty easy and there's no damage.
By the way, the gauge is awesome there!!