WTF is this for?

[Lex]

Yes, to the above.

 

[wildfiremaint]

Hi, take another pic with a ruler beside it so we can get an idea of its size. The thread looks to be too fine for an exhaust bolt.
I agree that its a throttle body idle
screw.

 

[Immortality]

I think it's from the exhaust as well, the factory system has a moveable joint in the center section held together with 2 bolts that are spring loaded.

 

[Derekthetree]

This thread sounds like an IKEA build!

"where does this spare part go"

 

[shane_3800]

The spring bolts are indeed exhaust bolts. They're used on conical gaskets.

 

[krusing]

its an exhaust bolt around the cat converter somewhere I think it came from

Correct as above ^^^^, there should be 2 of them.