Medyo mahal ang brake upsize. BUT: if you're not going to take the vehicle to trackdays, even just buying good pads (Bendix Metal kings) or performance pads (EBC Green Stuff) is more than enough for your car. Actually, with EBCs, even if you do go to trackdays, they'll be enough.

You can do simple mods like intake, headers, exhaust (your typical IHE), chip, etcetera for some extra response. It won't gain you much... maybe 15 hp if you keep it quiet (no ricey muffler), 15-20 if not (with a ricey muffler like mine ), but it's enough for some extra in-traffic kick. All-in-all, 50k might suffice for the IHE (all original or mandrel bent stuff) and 6k for performance brake pads pads. That's probably all the power you'll need for urban use, and more brake than you'll ever use.