That is pretty standard across all companies if you have a fully comp policy. There are exclusions to this though such as hire cars etc.
Do you have other mods as well as the
JCW kit? Alloys, Lowered, body kit? Most insurers won't be too frightened by the
JCW upgrade as it is usually on their systems as a MINI model. If you have other mods though you may be better off sticking with a
mod friendly insurer like AF.