My stereo/seats/nitrous kit got stolen a few summers ago and they didn't replace the nitrous kit but they replaced the leather seats/stereo.

Basically if it's in a "factory mounted" position i.e. a cd player in the dash and everything is bolted/screwed down they will reimburse you. So before you adjustor comes drill holes to show that you bolted down all your crap and they will pay you back even though it's not factory. I got quite a bit back from my insurance company but remember if you have too many vandilism/theft claims they can drop you.