Your engine needs to breathe, and the more cold air it takes in the better. Factory-style paper air filters are restrictive right off the bat; add a little dirt to the equation, and suddenly you're engine's gasping for air through a dusty layer of dirt and grime.

By replacing your restrictive factory filter with a high-flow air filter like a K&N, you can simultaneously reduce restrictions, increase power and improve mileage. That's because most aftermarket filters use oiled cotton gauze to provide superior filtration with drastically improved air flow.