When talking about modifications, I'm absolutely convinced that it all depends upon who you speak to on the day. Originally, Aviva were reluctant to quote on our lightly modded WRX, but on having insisted on talking to somebody higher up, who then referred to an underwriter (an endangered species in these days of call centres), excellent premium, terms and conditions agreed. Job done. Also recall referring to a "specialist" performance car broker a few years ago - all mods agreed, but front big brake upgrade resulted in a no quote!! Pure bonkers...