If you want to get maximum power out of your Opel Corsa 1.4i, there are several modifications to consider:

1) Upgrade your air intake system: Replacing the factory air intake system with a performance air intake system can increase airflow to the engine and improve its overall performance.

2) Install a performance exhaust system: Upgrading to a performance exhaust system opens up the exhaust flow, which can help the engine breathe better and produce more power.

3) Chip tuning: Tuning the ECU (Electronic Control Unit) can improve the engine's power output, giving you more horsepower and torque.

4) Upgrading the spark plugs: Upgrading to high-performance spark plugs can increase the energy output of the ignition system, resulting in better combustion and more power.

5) Install a cold air intake: Cold air intake systems bring cold air into the engine, which can increase power by providing a denser air charge.

These modifications can help increase the power output of your Opel Corsa 1.4i, but it's important to note that they may also affect the car's fuel economy and reliability. Be sure to research each modification carefully and consult an expert if you're not sure which modifications are right for your specific vehicle.