To increase power in a car, there are several modifications and improvements you can consider. Here are a few options:

1. Engine Tuning: One way to increase power is to tune or reprogram the engine control unit (ECU). This involves adjusting parameters such as air-fuel mixture, ignition timing, and boost pressure for turbocharged engines. Remapping the ECU can optimize the engine's performance, resulting in increased power output.

2. Cold Air Intake: Upgrading the air intake system with a cold air intake can improve the engine's airflow, allowing for more oxygen to reach the combustion chamber. This leads to better combustion and increased power.

3. Exhaust System Upgrades: Replacing the stock exhaust system with an aftermarket one can improve exhaust gas flow, reducing back-pressure and increasing power. This can be done by installing a performance exhaust manifold, high-flow catalytic converter, and a less restrictive muffler.

4. Turbocharger or Supercharger: Adding a forced induction system, such as a turbocharger or supercharger, can significantly increase power output. These devices compress air entering the engine, allowing more fuel to be burned, resulting in more power.

5. Upgraded Fuel Injectors: Replacing the stock fuel injectors with higher flow rate injectors can provide a greater fuel supply, enabling the engine to produce more power. This is particularly useful when other modifications, like a turbocharger or supercharger, are added.

6. Performance Upgrades: Upgrading various engine components like the camshaft, crankshaft, pistons, and connecting rods can help improve the engine's power potential. However, these modifications should be done carefully to maintain reliability and ensure compatibility with other engine parts.

It's important to note that modifying a car's engine for increased power may have legal implications, and it is crucial to comply with local regulations. Additionally, these modifications can potentially void manufacturer warranties and may require expertise and technical knowledge to ensure proper installation and tuning.