On my old 197 Cup;
Fronts: AP Racing 310mm two piece discs and DS2500 pads
Rears: Standard discs and pads
HEL brake lines
Motul RBF 600 fluid
On the Megane (same callipers etc.) the set-up stops it just as well if not better than my old 197.
Fronts: Godspeed 330mm brake kit with DS2500 pads
Rears: Standard discs and pads
HEL brake lines
Motul RBF 600 fluid
imo you don't need to do anything to rear on these cars. They do very little, really just keeping the car straight or catching your slide if traction controls on.