What is this? How to fix or plug the hole/exhaust leak?
 

I drove it to work today as it is a super nice day here and noticed it felt a little flat on power and possibly heard an exhaust leak.

At lunch I take a look and happen to bump this and it was really loose then then came off completely. IIRC it was for the cycling valve or venturi and has been capped off for a long time now.

The problem is how do I fix it or can I just plug up the hole from where it mounts and where does it exactly mount?

Is that the 'sniffer' pipe that comes off the crossover and up between the firewall and headers? If so, you can cap the port off at the crossover with a lug nut. This is what I did after reading about it many times here, and it seems to be leak free.

Looks like the CO test port -- used for sampling the exhaust (and checking back pressure). If so, you can unscrew what's left of it on the cross- over and cap it with a lug nut.

You beat me to it. +1

Yep! I just found the diagram of it.

Thanks guys!!

Isn't that also where some tap in for wideband?

Also, would that be far enough down the exhaust path to not affect performance or would that have a direct affect?

no, to hot and to much pressure for it to operate properly,

wideband goes after the turbo

Makes a good place to put an EGT probe though! Search for Laust's setup.

you can put a 14mm 1.5 pitch lug nut onto it to seal the hole in the crossover. A spare from your car will work fine.

Ok thanks Doug.