1. Filter Facts
All engines - normal and racing - require rpm depending on a constant changing volume of airflow. The fuel management system will provide the right air/fuel mixture of aspirated air volume to enable maximum power output by minimising or avoiding airflow restriction. Non filtered air can cause engine damage. This is the reason why filters are in place to protect the engines during their planed lifetime.
The filter has to absorb as many dirt particles as possible without restricting the airflow required.
A reduction of airflow will lead to powerloss.