The AEM 21-754DS Performance Cold Air Intake System produces horsepower and torque gains by replacing your vehicle's restrictive factory air filter and air intake housing. This air intake system was designed, tuned and dyno-tested to fit specific BMW 335I models. Air enters the system through an oversized AEM Dryflow synthetic washable air filter for outstanding air flow, filtration and performance. The air filter is placed into an open-bottom AEM air box which is designed to protect the air intake system from engine bay heat while also helping to produce a more aggressive engine sound during acceleration. The air intake tube is made from lightweight, yet durable, high-density polyethylene and is aerodynamically engineered to flow air freely into the engine's turbo inlet. This air intake system was developed to accommodate the engine's factory emissions control devices including the mass airflow sensor. The tapered cylinder shaped AEM Dryflow air filter is made from an oil-free, synthetic filter media that can be used for up to 100,000 miles before cleaning is needed (depending on driving conditions). The air intake system is easy to install with commonly available tools and it is backed by AEM's Lifetime Limited Warranty. Some AEM air intakes are not legal for sale or use in California and other states adopting California emission standards, while others are 50 state legal. View the 21-754DS vehicle applications to determine the legal status for each vehicle.