For anyone wanting to know which AEM filter fits, either of these will fit the K&N cold air intake that is designed for the 996:

AEM 21-204DK (red)

or

AEM 21-204BF (black)

This K&N is a 3.5 inch flange. This filter has that, and is 6" and 5.125" on each end (cone shaped). The height of the filter is 5.25" and will not be too big to fit. You will still have some room around your oil tube. I would recommend getting the AEM 1-4000 Dryflow wrap for a perfect fit of the above filter to keep it from rain/water.

Cheers.

Swaff