What is the most efficient way to increase horsepower in an Audi A3?

I want to improve the performance of my Audi A3, but I'm not sure what the best method is. What would be the most effective and cost-efficient way to increase the horsepower?

Upgrading the engine's air intake and exhaust systems is the way to go. This allows for more air and fuel to reach the engine, resulting in a noticeable increase in horsepower.

Installing a performance chip can provide a significant boost in horsepower. The chip reprograms the engine to improve its efficiency, resulting in better performance and power.

Adding a turbocharger or a supercharger is another way to increase horsepower. Both force more air into the engine, resulting in a significant power increase.