The simple answer is that it depends on your vehicle. Improving the airflow to your engine has been shown to increase horsepower. That being said, we don't publish horsepower numbers because of the inaccurate and outlandish claims made by many of our competitors. Instead we test to the ISO 5011 Filtration Standard and publish the airflow, efficiency and capacity data on the product pages found on our website. This is the internationally accepted standard for testing filters and intake systems, so we can hold our competition accountable if they make an incorrect claim.
Typically, the OE stock air box and induction tube significantly restrict the airflow. S&B designs its intake kits to minimize airflow restriction, allowing the engine to breathe easier. Actual horsepower results depend on a variety of factors such as environmental conditions and the presence of other modifications done to the vehicle. Typically, intakes are used in conjunction with modifications such as exhaust and/or engine tuning calibration products, to make significant increases in horsepower, and the actual results will depend on the effectiveness of those other products.
S&B does not publish horsepower results specific to each part because the majority of our competition makes outrageous horsepower claims that are unsupportable and are often accompanied by the disclaimer "Up To, As Much As or Results May Vary." Dyno results can vary depending on factors such as tire pressure, oil and coolant temperature, the placement of fans in front of the vehicle, and even the manner in which the vehicle is strapped down. Some dyno results can even be made to show different results through the use of different smoothing factors and/or correction factors. Since there is no standard for dyno testing, it is difficult to hold our competition accountable for their inflated claims, and virtually impossible to fairly compare dyno results from different companies.
S&B utilizes its 1/2 million dollar, climate controlled lab to test its intake kits and filters to the same standard (ISO 5011 Test Standard) used by the OE manufacturers, so there is substance behind S&B's test results. S&B publishes two (2) critical results: (1) Airflow and (2) Efficiency.
(1) Airflow Rating: This rating shows how much the filter and/or intake improves the airflow versus stock. By improving the airflow you will improve both the performance and fuel economy of your vehicle.
(2) Efficiency Rating: Protecting your engine while dramatically improving the airflow is S&B's competitive advantage which is why we post the efficiency numbers along with the airflow rating. The efficiency rating shows how much dirt our filters will stop. Our minimum goal for efficiency is 99.0%.