Help! What is this thing????

It's stamped "K-Tuned" on the front, this is on the front of my '07 Si FA5, recently purchased, - below the intake behind the radiator. It appears to be capped on one end, the other end looks to be maybe a cable or small fluid line running back towards the firewall / cabin. I know the picture is ****, I was hoping someone would recognize it immediately. Many thanks in advance!! I have more "what is this fackin thing" questions, but this thing really blows my mind.



Happy to be a part of the forum. Cheers!