If I knew what it was called I wouldn't be asking. Searching for tube only gives about 2 million posts, one of which is related to what I'm asking about. But even that thread only contains people who don't know what it is.
If you search in the mazdaspeed6 section you wont have that many threads to look in. Also if im not forgetting it was just used to test things when mazda put the car together and now serves no purpose.