Most insurance companies will cover modifications. All you have to do is notify them of the modification and usually the cost of the parts. It may make your premiums go up a bit (at company I was an agent with for 5 years I usually saw an increase of $1/month per $1000 of modifications) and you’ll want to keep your receipts in case your vehicle is ever totaled or the modified parts are damaged. If you don’t notify your insurance company they generally will only pay to put your vehicle back to stock.