Gentlemen and Ladies,
This guide is intended to help anyone install their new K&N, aFe, etc. replacement air filters. This is also intended for the 335 with a standard air box, or, NOT replaced with a CAI.
Reasons for getting a high-flow filter:
1. Our cars have a TURBO. This means that they'll run a bit hot over their NA cousins, along with needing more air for more proper combustion with the forced induction. I say let's give it to them!!
2. As others have said, it won't void your warranty, will give you (slightly) more hp, (slightly) better gas milege, and doesn't have to ever get replaced. So it pays for itself after 2-3 replacement filters. I've had a K&N in my Corvette, Mazda3, Altima SE-R and previous 328Ci, and have experienced noticeable gains in hp, torque, and fuel economy after their installation.
3. It's so easy (yes, if a caveman drove an F30, he could do it to!)
Steps:
1. Pop the hood
2. Locate the 4 silver tabs holding the top of the air cleaner box in place. If you are facing the vehicle looking into the engine bay, there will be two on the right side, one on the top left, and one on the left side.
3. Pry them loose using finger pressure. Be careful that they stay in place. I almost lost one into the depths of the engine bay!!
4. Gently lift up the top of the air cleaner box and remove the stock filter. I found that I had plenty of room to remove the old filter without disconnecting anything.
5. Place your replacement filter, drop the lid on top of it (it guides itself back into place with its tabs), lock it back in place with the tabs, and you're finished!
6. Place the accompanying sticker somewhere conspicuous on the car. You'll get 10 hp from that mod alone!!
Enjoy, and happy motoring!
