Oem Bmw Filter
http://www.ecstuning.com/BMW-E46-330...liter/ES35397/

K&N filter
http://www.ecstuning.com/BMW-E46-330...liter/ES11019/

Bmw Performance Filter
http://www.ecstuning.com/BMW-E46-330...liter/ES35342/

I'm thinking OEM.. but if you guys say other wise I may consider something else.