I haven't got the 1 litre engine, I have the 1.6 diesel and I have had it remapped by a reputable long established garage in Donny. Now, I can catagorically tell you, the premiums do NOT necessarily go up by that much, if at all. The fuel consumption is barely affected too. For normal road use in a "family" car like the BMax, you will use the top end power so rarely it honestly made sense for me to have it done. In fact I didn't get it done for top end power/speed, I did it to ride a more progressive torque curve when travelling to Spain n France. I would say, don't be put off and a lot of places will offer to put it back to standard with your money back if you don't like it. Oh and a real small note, you don't need to tell your insurance as they will never find out anyway, unless they find your receipt.
1.6 tdci, remapped to 120 bhp, Panther Black Titanium with rear view camera, nav pac and front sensors. Always willing to stop & help in any situation I can. Karma is a beautiful thing.