Adrian flux put mine up by £35 for Viper Kit, Supersprint Mani and Supersprint exhaust. The trick with performance parts is that when they ask for the BHP increase you say there isnt one, just noise. They do not check for little things, if you bolt a turbo on and say its added no power they will check(if possible) when you claim.
I'm an insurance broker and you need to bare in mind that we pay out nearly £200 an hour to the assessor, you think we're gonna pay him for 4 hours while he measures the BHP at the wheels? No. Also, if your 182 has 190bhp at the fly as standard, although its not likely, then you crash and we do decide to measure it, how can we prove that your car didnt have it anyway. We cant so we have to pay out or the FSA/FOS rape us.
One last thing, you will no doubt have heard horror stories of insurance companies measuring bore depths and that the cc in the block is the same as it should. They are all lies, it costs us too much to do it. Just declare the mods and say they havent added bhp unless its too obvious.
P.S Dont ever worry about listing mods in car mags, we cant prove that the print is correct.