I guarantee you that not "everything" has been done before, even when it comes to body modifications.
It's posts like this that push people away from wanting to post about new ideas, or variations on old ones.
I don't think the S13 flares as they are would suit an S30, but a similar look probably would. Like taking a ZG flare and extending them farther and more squared off than they are out of the box.
Two of my favorite wide® body modifications on the S30 are the Subtle Z kit, because well, it's subtle, but gives it that, "I know there's something different, but can't quite put my finger on it" look, and the YZ kit, because it's just bold, and actually flows extremely well with the original shape of the S30.