And if it was a 200 series 3.5 it would go to the charcoal filter depending on the intended market.
3.9s as u know have the filter in the engine bay and the pipe goes into the plenum so much more environment friendly.
Is it the drain pipe for the sunroof. Easy way to see, drop some water down the drain under the sunroof rubber seal and as long as they are not blocked up you will see where the water comes out.