Let's restate that suggestion. On a given engine, it's possible to select passage section areas to achieve peak torque (volumetric efficiency) points at specific rpm where such boosts are desired.

Generally stated, volumetric efficiency is a comparison (in units of percentage) of the amount (mass) of air ingested by an engine on each intake stroke compared to the amount (mass) of air that ...

All are important to proper tuning. We can also determine volumetric efficiency (VE), which helps determine carburetor and manifold sizing for the application.