what is this thing?? and why does my sr only have an empty bracket there??

 

AIV Valve.

You don't need it. it is just an emsissions device to let air into the exhaust at idle.

It was on mine when i pulled my motor from the clip but i didn't know it HAS to be removed or relocated because the stock location the pipe contacts with the steering column and you can't steer.

 

If you miss it, you can have mine.

 

Other than that, there is a pipe connects to the turbo outlet, just 2 or 3 inches below the o2 sensor, you need to remove that as well, and get a big bolt to block off the hole or you can weld a penny on it. Also, remove the lower head shield on the turbo, it won't clear the steering shaft.