The easy answer is "What does your policy say?". If you follow that, you cannot go wrong.
Some (like Admiral) want to know about anything that isn't on a base-spec car: In the case of the 350Z, that would include Rays if fitted as an option. In the case of an average 3-series, it could take a couple of pages! Some insurers (like A-Plan, who I'm with) want to know about mods, but unless you're going for massive power they won't load the policy: For example, my track slag has no interior which is covered under 'interior changes'. Some insurers (like Sky, who I was with) didn't care about factory options on my 911, but did care about official extras I'd added after purchase, like a sports exhaust.
Follow the policy wording. Really, to be safe just tell them about everything: Some will care, some won't, but either way at least you'll still be covered. Never make the assumption that it's so small that they won't care (like a stubby), as that's how you end up with issues.