Why on earth on would you want to exchange the filter for a k&n? If you're worried that the metallic blitz SUS filter is too open and lets through too many particles, buy the blitz LM Intake
Anyways, the INSIDE diameter of the lip on the blitz filter (the filter is thread on the outside of the Intake
housing, so you can't buy anything smaller than this) is 54cm.
The hight/length of the filter (including the lip that sits outside the Intake
housing) is almost 13cm.
This is measurments taken off the blitz LM filter.