hey guys I have a question that someone hopefully has some insight on:

I see a lot of people swapping to a single turbo from the twins because of the obvious reasons (performance, reliability, etc)

My question is... will connecting the vacuum lines, solenoids, and manifold back to the original twin set up pass smog without any issues??

Granted everything else is stock or has no issues with smog..

 

If the car has been changed out to a single then most likely the ECU has been too.

Cali needs the Emissions junk to pass,so if the car even has a aftermarket exhaust you are screwed.

 

so everything can be stock essentially...

but..

If you have an aftermarket exhaust. You're still screwed?

what if the aftermarket has a decent cat in there?

 

Most guys do not run a Cat if they have taken off all the emissions equipment.

If you retain the cat and it's essentials to run it then you can tune an aftermarket ECU to get the specs needed to pass.
But then again,as I said..California..(hard to pass,so I hear.)

You may want to start a search in the 3rd gen specific and archives.There is a ton of info on this.
I don't want to steer you in the wrong direction.

 

You pretty much nailed it with this statement. All mods need a CARB number.
Swapping to a single turbo will fail the visual but could pass the sniffer with a cat and stock ecu.

Cat-backs are fine.
The cat needs to be a direct fit 50-state legal one with a recognized model number. That only leaves a handful of models. None of which are designed to keep up with the rest of a free-flowing aftermarket exhaust.