Airfilter BHP rating: 310 hp Why foam? Because, compared to paper or other filter technologies, reticulated polyester foam achieves optimum performanceagainst three key criteria: Maximum Air Flow The ability to allow air to pass through without causing a large drop in pressure. Cleaning EfficiencyThe capability to arrest a high proportion of airborne dust while feeding the engine clean air. Dust Load-up ToleranceThe capability to absorb a large amount of dust without reducing air flow capacity.