Does water circulate through the OEM intercooler? If not, what is the connection that faces the rear of the motor? Where does it connect?

 

It does not circulate water. I belive it is for emissions. It connects to the top of the dynamic chamber (upper intake manifold) directly below the fitting on the intercooler shown in the picture.

 

OK, so is that a vacuum line type connection then.

 

No it does not flows water. The coolant goes directly to the turbo.

 

That connection is for the air supply valve. It feeds air from the intercooler to the intake manifold during heavy loads from the power steering or during hot start. If you dont have PS then cap both ends.

I still have my PS but capped that hose long ago. I've never had the engine die or even stumble at full lock.