Mann is OE. K&N lets in more air, but the OE Mann seems to be better at particulate filtration. The design of our cars are not starved for air(unless you have a aftermarket turbo/supercharger). Either filter will be fine, and you wont notice a difference. Just stay away from anything that you have to oil. It does more harm than good.
A forum community dedicated to BMW owners and enthusiasts. Come join the discussion about Bimmerfest events, production numbers, programming, performance, modifications, classifieds, troubleshooting, maintenance, and more! Bringing the BMW community together.