Many good folks advid=se me to go for the OEM air filter... but I went for the K&N for some reasons...
I received the filter yesterday.. and I saw that the flux restrictor fits not that tight... ( so I thought that would be nice to have the specs in case of losing the original one. I draw it in SolidWorks 2016, and exported in STL.. so anyone can 3dprint or do it on a lathe.
It is made of rubber.. but it would do fine on ABS or PLA
Keywords: restrictor, K&N, air filter, su-5589, 087018-1
SW:
https://drive.google.com/open?id=1k0WrhgboYYwFYTyByronbCludchb9hdg
STL:
https://drive.google.com/open?id=1f2UXWc3DdKu6U-4QCkIu7CDunUml6nBN
:)
in millimeters