Want a bit more pep from your BMW without a major mod? This K&N air filter is a popular first upgrade. Part number 33-2070 fits a ton of BMW models from 1990 to 2006, including the 3 Series (323Ti, 328i, M3, etc.), 5 Series (520i, 525i, 528i, 530i), 7 Series (728i, 728iL), plus the X3, Z3, and Z4 (check the full list to be sure). It's a high-flow, cotton gauze filter that lets your engine breathe easier, which can mean a little extra horsepower and throttle response. The big sell? It's washable and reusable. You just clean and re-oil it every 50,000 miles or so (depending on driving conditions), so you never have to buy a disposable paper filter again. It's designed to work with your car's stock electronics. A simple, cost-effective performance and maintenance upgrade for your BMW.
