[Dantilla]

The entire power train has to work together as a team. With poorly designed engines, there is usually a "choke point", one specific area that's limiting power. I know on the 944S2 that the factory filter is capable of more airflow than the engine can use, so there is no benefit to changing the filter or box, unless there are other dramatic (expensive) changes. I don't recall if this is the case with the 968, but with most Porsche applications, the factory did an admirable job, and didn't leave any cheap horsepower on the table. Many cars won't benefit from an intake change by itself, or an exhaust change, but will see impovements when both intake and exhaust are modified, allowing the entire system to breathe more freely.

The turbo engines are easy to modify, because all you need to do is increase boost. Porsche did an excellent job with the normally asperated engines, so you may want to do some research before you take a drill or sawzall to your car.