Just about every BMW can increase horsepower in the range of 3 to 10 horsepower simply by exchanging your stock paper, air filter for a K&N Replacement Air Filter. The K&N filters are less restrictive than stock filters allowing your engine to "breath" better thus producing more horsepower and torque. K&N's unique fabric screen filters out the smallest particles of dust and dirt even better than stock paper filters. Best of all, K&N Filters are guaranteed for the lifetime of your car with regular cleaning and oiling, so you never have to buy another filter.

In general we do not recommend the purchase of "Cone Style" filters from K&N or other manufacturers. In nearly 100 Dyno tests we seldom found any increase in horsepower over stock paper filters and in some cases we actually recorded a loss. Once a car comes up to operating temperature conical filters suck in the hot engine air in addition to greater volume of hot and humid outside air. When you are on a long trip (or on the track) on a hot day, and the engine is already running a bit warm, the last thing you want to do is feed your engine increased volumes of hot air. Many people are fooled since they install their cone filters and start out on a cool morning with a cold engine and feel a new rush of power... this quickly disappears once operating temperature is reached. The few exceptions were in cases where the conical filter was ducted with fresh outside air and in addition was in some way insulated from the engine heat. Since the conical filters generally cost as much as $100 more than a Replacement Filter, the decision in this case is easy.