Just so you know, in the event of a claim they wont replace the modifications... they will put the car back to standard. All they are doing by you declaring them is sitll agreeing to cover the car. Admiral offer Modifications cover but it is only up to £500 but this is an optional extra. Below is from their website. Admiral's Modification Cover contributes towards the cost of replacing non-standard parts or modifications fitted to your car. Buying Modifications Cover To add our Modifications Cover to your policy, make sure you choose the option when you buy your Admiral car insurance online - or tell the advisor if you phone us for a quote. Compensation of up to £500 or 10% of the vehicle market value, whichever is less Compensation for disability modifications up to £2,500 or 15% of the vehicle market value, whichever is less Maximum of one claim per policy term subject to a £50 excess Choose from our extensive list of modifications including Alloys, Exhausts, Spoilers, Bodykits, plus Disability Modifications.