1 x Pipercross Competition Air Filter ONLY – C504D (No Base Plates Included) Pipercross Competiton Filter PX500 – Limited space twin carb air filter Main Benefits. For use in Universal/Custom Applications. Description The PX500 range is designed for twin SU, IDF and DRLF applications where only one filter is required for both carburettors. The filter is made from Pipercross multi laminate competition foam and supported internally by an expanded metal cage. The filter element and baseplate are ordered separately. Always use the largest element possible and ensure that there is at least a 19mm gap between the mouth of the trumpet and inner face of the filter. About Pipercross Pipercross has been making high performance air filters for the motor sport and domestic markets for over 25 years. Based in Northampton, England Pipercross is situated in the country along with some of the biggest names in motorsport engine design and manufacture in the world.