I am afraid you missed my point
Stretching 1/2 inch tubing over the input of the Enhiem is just as bad as no res at all.
Your are restricting the input side of pump unless you go to a bigger hose size.
Having a Res in line anywhere is pretty much useless (other than as a air trap) if the hose feeding the pump is still smaller than what the pump calls for.
Also according to the latest diagram you plan on using a push/ pull fan set up on your rad, Both sides must be shrouded if it is to work correctly.
Aardil