While on the Dynojet, we conducted a quick experiment with a K&N air-filter element. After a couple of pulls, we swapped our generic open-element filter for the K&N--we only changed the element, not the cover or baseplate of the air cleaner. The filter produced a measurable 6hp improvement on the chassis dyno. An open-element K&N is probably worth at least 12-15 hp as compared to the factory closed-element, single-snorkel air cleaner that came on our Chevelle. The comparison of the Dynojet and the On-Board Dyno were made with the K&N filter element already installed.