I tell the bass studs everything. Only significant differences on ours are TT exhaust and non OEM tyres. (Toyos) on OEM wheels. I ask for written confirmation that they have any changes on their records, which they have provided.
No increase in premium but they cannot claim that are not aware of the changes in case of a claim. I recommend declaring all significant changes to be honest.
Final note: check prices each year: my Jag quote for this year was almost double last year, with no change in circumstance: changed to Swinton. When I rang Hastings to cancel they said they'd try and match Swinton. I politely
informed them that I want their best price up front, not in the wake of a competitive quote.
Car insurance premiums:
the single advantage of getting old.