Well as an insurance broker with 35 years experience I would like to think I know but it's up to you of course. No harm in telling them but the problem with the internet is you can only tick boxes. If in doubt speak to a human at your insurer and get their confirmation.
Insurers factor in all the available factory options when deciding the group rating but they cannot factor in the unknown which is why post-manufacture mods have to be declared.
I thought this would be the case, up until this renewal I have only ever declared the mod's I have made, when I spoke to them yesterday they were happy enough to take the other items off for me when I said they were fitted as standard for the model.
I will have to get back in touch with them and get a definitive answer. Have already managed to knock £80 off the renewal with some discount they applied so I will see how much of a difference this makes and if they can't provide an answer then I'll have to decide if its worth the risk of not declaring.
I think I'll side with the expert on this one . I always assumed that you state the car you have and its approximate value. Factory fitted options are not modifications, and I don't remember ever seeing anything on insurance sites about declaring options, it's only ever modifications that you declare from what I've seen.
On the comparison sites I have to check the mod's to add the exhaust etc and on each of them there it has other items listed such as 'Alloy Wheels (optional extra)'. I don't know if its just a ploy to fleece those who aren't savvy enough to question it.