So on the wrx engine theres a reservoir tank for coolant so that coolant can cool the turbo after the engine has stopped. there are two lines on the top that both went to the radiator or expansion tank, but considering the large distance between the engine and the radiator what needs to be done?

Is it to cool while the engine is still running like a turbo timer system or an auto recirculating system once it's turned off?

it curculates after the engine turns off to avoid ruining the bearings

I don't have an answer for you, but I would recommend switching to the plastic tank as the fittings on the metal tanks tend to corrode and leak eventually. Cheap insurance.

Also the paint on the inside of the tank (yes there is for some reason) will begin to flake and you'll have paint chips floating around in your coolant.

Or you could cool down your turbo properly like normal people

Side note the Davies Craig water pump controller after runs the water pump and fans for a couple minutes or until its below a certain temperature threshold.

There are quite a few subaru turbo 914 members. One of them will reply soon I'm sure. DBCooper has a build thread and so does Amenson. Both running and driving for quite a while now.