Hey, I am getting parts for the 90K service, one of which is the air filter. www.bimmerparts lists air filters from Bosch, Mann and Mahle, all list for $20.60, but bimmerparts price for Bosch is $8.86, Mann is $15.67, and Mahle is $10.20. Any idea which is better? I'm guessing that more expensive has very little relationship on "best" here. Any thoughts? -Ian Duff.