Well, actually no, at least in 530d. It might be a bit easier in a 520d due the smaller size engine.

Besides the engine acoustic cover, you have to remove the strut bar, and to remove that, you have to remove the plastic parts over it (cabin filters and their housing).

I personally don't think you would achieve much or anything with the K&N filter.

- Antti -

 

I was thinking about changing my own air filter in the next couple of days. If i bother, maybe I can take some pictures for you. I havent done it before on my bimmer, but I guess I'll manage to find it some way ;-)

 

I am running a 530d with the K&N filter poster above.

I don't know if it gives you any more power, even if it does, it will just be an HP or 2 so i don't think you will notice any difference.
It is easier in cleaning though. After 20k miles i just took it out.. banged it on the curb a few times to clean it out and put it back in. No need to purchase a new one.

It does give a bit louder turbo blowoff sound

 

yeah i think you're right about the extra bits that have to come off.

 

I don't believe the K & N filter is a good idea because they have to be oiled and this can get deposited
on the MAF sensor and will ultimately screw it up.

Winbar

 

Sorry mate but that is just a load of bull.... I don't believe that for one second. If you would ever have a properly oiled (new) K&N filter in your hands you would think otherwise.

Greetings from a happy K&N user for over 50k miles.