S front brake upgrade is worth it, been done many times by many people. Nowadays I have to watch who's behind me when I hit the brakes hard.
If you want even better brakes, get the Girodisc rotors which are even bigger than stock S brakes but requires at least 18-19" wheels to fit.
If you want even better brakes, get the 6 pistons Brembo GT kit which is around $5000USD.