Poking around on Prime Portal looking over the Btr-90 pics.. wouldn't that make a great kit , Mr Tamiya!
I came to this one, #102.
The fitting in the center of the image, with the curved chormed pieces and the rubber endcaps.
What is it?
If the end caps off it could be an air sampling inlet.

http://data3.primeportal.net/apc/yuri_pasholok/btr-90/images/btr-90_102_of_169.jpg

Anyone know what this is?

Mike