Disclosure of information.
As an afterthought to my previous post.
There is probably no reason as to why you cannot inform your insurrer of any minor mods you make to your car once it has passed its sva/iva.
It will be highly unlikely that it would affect your premium or withdrawal of cover.
If you go for a megga increase of engine size or type then it will be accepted that a higher premium will apply.
Only a very young or inexperienced driver is likely to have a policy declined due to engine size.
The average insurance clerk would not have a clue about sva/iva regs. When you tell them about a change of instument pannel or the addition of switches. It will just be entered onto you file.