First, I have to say that the stock PC is quite good and as good or better, than most stock cords in that regard.
That said, some, me included, find using an "after market" High End Cord even better.
My all-time personal favorite for the REF-18/REF-20 is the WyWires High Current Juice II with the Copper Male 3 prong Plug. I much prefer the Copper over the Brass Plugs that are so common. You can see that plug in the photo at the beginning of this thread.
It seems to take the Magic one more step.