Adding my O/H to the insurance on my Discovery, declared mods of springs/exhaust/LPG etc, unlimited personal/commuting miles and 5000 business miles made no difference to my insurance.
I had the poor girl on the other end of the phone running through hoops of "what if I remove the 6th and 7th seat" etc, all made no difference.
Apparently the business miles and a claim which comes off in December are the factors that make my insurance higher. Cost me £500 fully comp, business use, modified.
Ironically the GF had a quite from one of these women-only places, added my name to the quote and it went down by 1/3rd!