I've decided to make my Nissan a pure Z-car by removing all the Nissan branding. First job was to replace the Nissan-branded centre caps on the Rays alloy wheels.
Replacements were purchased from eBay and are a perfect match for colour and finish.
Installation means taking the wheels off. Loosen the wheel nuts, jack the car up using the Nissan jack at the correct jacking points (two little indentations mark this roughly underneath the front and back of the car door), and then remove the wheel nuts to take the wheel off. Good opportunity to use some wheel cleaner to thoroughly clean the wheels where it's usually difficult to reach when they are fitted.
The centre caps are held in by a broken circle of stiff wire, which you can see in the back of the new one here:
Fron the back of the wheel, press inwards a couple of the tabs and you can push the entire cap straight out. To refit, simply line up from the front of the wheel, and press into place.
If you're paranoid about breaking a tab off the caps, you can remove the wire (which is how I did the first two wheels until picking up Wayshot's advice - I used the simpler method above for the other two). If you want a more complicated way, then from the back of the wheel, carefully use a flat screwdriver to unclip the wire at one end, and then the other, and lift it out. It clips in three places. The centre cap will then press out from the back. Fit the new centre caps by pushing them in from the front, and then from the back fit the clip back in place. It's tempting to use the old clips because they are already bent in but I decided it's worth persevering with the new firmer clips just to ensure no-one can ever prise them out from the front. Pull the clip in to a tighter circle and ease into the back of the centre cap. Get the bottom bit secure first, and then bend in one side and then the other to catch into the other two places.
Wheel with new Z centre cap looks like this: