If the option is available, forced induction (turbocharge or supercharge the engine). Otherwise, basic bolt-ons (air intake, headers, exhaust) can increase hp/tq, but generally the increases are quite minimal.
Got another update here on the Mazda bought some more parts for her. Picked up a driver side control arm, thermostat, intake gasket kit, bottom motor mount, PCV valve, oil catch can and I got an easyguard pke push start alarm system for her. No need to ever touch the key again the alarm system...
Also if you search our Mazda5 Forum, you should find more info regarding increasing the Mazda5's power output.
Good luck and at the very least, it's worth exploring options.