Please, for the love of god don't listen to anyone saying "carbon fiber this, carbon fiber that" not EVERYONE can afford a $3k+ Bodykit on a $22-23k car!
Anyway, my suggestions it to have TWO available options (If not, take the one you like the Best, FiveAxis!)
Street Kit: Subtle lips here and there, i know FiveAxis has great vision and "flow" in terms of designing their kits to ADD to the body of the car in a subtle yet different manner, quite beautiful, actually. ALSO IMPORTANT: PLEASE a "DuckTail"! I absolutely (and i'm not alone here)

ADORE the AE86
TRD-Style Ducktail! it just Adds that cherry on top that the car always needed!
Also, on that front-fender note, i see the FRS concept has a "step-cut" on the side of the front fender towards the front of the doors that makes the fender arch just that more dramatic! I love that! Add that!
Hardcore Kit: Go crazy! charge whatever you want! perhaps, like the poster above me said, make those tall front-fenders that mimick the Original FR-S Concept! go crazy!