If you're not upping the power, some decent pads and discs, tyres, brake lines and uprated brake fluid should be more than enough at stock power levels unless you're hitting the track or doing a LOT of heavy fast road braking.
Remember WRX 4pots can lock the front wheels, so they're not short on power... only issues after that are feel (hence braided brake lines and uprated fluid) grip (hence tyres) and fade/ overheating (in which case DO go bigger).
There's always the BLING factor with bigger brakes as well!