Richard,
Thank you.
I do understand that the ventilated Payload Bay door cover have openings in such a manner that it is assumed to have the EDF flushed with the Rear Bulk head.
However, the model still has all those Holes up front (Top Nose holes and the Large Bottom one).
I am planning to move the EDF perhaps one inch rearward but, not that much as I do not want to have to move the batteries all the way forward.
Should it was the case that the model did not have those holes up front then, I can see that the Payload Bay door cover would be the only source but, it no longer is the case.
Remember this model that I have is a Prototype within itself!
Carlos