Let's see some proof... anything done to a factory setup alters its value... I'd like to see where it is documented that there is a degree of depreciation for the degree of altercations taking place. If it's not factory, it alters the blue book value regardless of what's done.

Who cares anyhow? If you're building a car you are most likely doing it for the love of the sport not to see how much you could sell it for. If you've done a hybrid then you definitely won't be selling it to the general public but rather other enthusiasts.