costs me about £80/year to declare the prospeed (non-decatted) on the 182 with D/L - but when I rang round last time, they were still a good £300 below anywhere else (a lot of places wouldn't quote - which is ridiculous!). Car is actually the wifes, all in her name, but we're both 29 with a load of NCB in a reasonable post-code...
Silly thing is, that will add no power, but to revo the LCR (+50BHP) will only be £100 extra - can't really work that one out!
Seems a lot of insurers are really not keen on modding newer cars at all...