Gotta get rid our own "spare tyre" if there's any. From 90kg to 70kg...20kg less not only can let our car go faster, we can also go faster ourselves
Not to mention healthier..more good looking..more confidence...more girls (T&C applies)
Since your car is auto...I guess changing the filter, extractor, ignition coil or cable, better plugs, lighter rims will do. Won't improve so much, but there's a few hp and torque you can get, and able to feel them. If major mods, like Izso mentioned, not worth it if it is an auto.
Reminder: adding GT wings, 17" rims, and all those booster booster things don't work. Sammi cheng's song might work though