As other's have already stated, you're going to take a beating and your mods can detract from the sales price, as well as turn some if not most potential buyers off. Personally, I'd return it back to stock before trying to sell and sell the removed parts separately. As far as the spoiler & other small mods you asked about, again, I wouldn't do them and, if you've already purchased the parts, sell them separately.
Good luck which ever way go ...
