The rear add-ons and side skirts are the same from 03-08 model, but the front lip is different. However, Nismo has discontinued making authentic Nismo front lip for 06-08 Z and also discontinued making side skirts as well.. I was lucky to enough to get one of 2 front lips left in the US last year.
But you can get a very good quality and fitment from Shine Auto Project. I currently have 06+ authentic Nismo front lip, Shine Auto Nismo replica side skirts and rear add-ons.
Here are a few pictures of the lip kit.
new-wheels-t486877.html
I installed these myself. And as you can see, the fitment for Shine Auto replica pieces are pretty good. However, the authentic Nismo front lip fits like a glove. I wish I could have gone with all authentic Nismo parts, but the side skirts and rear add-ons were discontinued, so I had to go with replica.
If you want to stick with authentic Nismo parts, then you just have to search for used parts through this site and other sites.