I'm with coseco insurance, and every 6 months when I call to make changes (car going in and out of storage) they ask me if any of my cars are modified. Due to the paranoia.. my cars are more or less stock now.. BUT.. my last call with the ins co, I asked about making modifications. I specifically said suspension and wheel upgrades and the agent asked what the value would be.. i said 3-5k... She put me on hold... came back said so this is for performance reasons.. I said yes.. She put a note on my policy and just said to give them a call once I have made the modifications..
So basically for now I am going to assume I have the green light .. so mebbe next year coil overs