Wanted to ask everyone out there how much their insurance changed when they lowered their cars/uprated the springs?

Also, do insurance companies want you to have them fitted by certain garages?

Want to start modding my Signum but a bit worried that the insurance will sky rocket.

For me and the missus we pay £200 a year for a 2.2 Direct (petrol) at the minute and hopefully don't want it to go up!