OH WOW, dude im so sorry to hear that.
Ive been in a similar situation before, where the other guy was to blame and I got payed out. (you always do when its not your fault).
Sadly though, most insurance companies pay the 'market value' of the vehicle and they don't seem to care about personal valuation and rarely take performance upgrades into account either
I was lucky in my case because the parts I bought were not yet installed, besides which, it wasn't a write off.
I cant speak on your behalf, but I would definitely touch base with the insurance company to clarify exactly what the settlement figure is.
Nothing is certain until you know, so don't conclusion jump at this point, Just make some calls and go from there. They could end up making an exception if you have enough proof of purchase.
I Hope all ends up going well for you man.