CCI can be competitive but more so if you were with them prior to the policy change. If so, you have to elect to remain on the old cover type.
They did also inform me that the rates were heavily affected by commuting. I elected to include commuting in mine and it was worth while for the slight increase.
Main thing for me is that they have no interest in power once you are over 750bhp. They quite sensibly know that 2000 bhp or 750bhp, it's not really going to change your risk factor to them as the car is already in the ridiculous performance league.