I've just fitted an ez down kit and noted a few things:
The top screw holding the original arm was not budging with a ratchet or my 18v impact driver (mechanic friend said he'd had success before with one) so I resorted to mole grips (vice grips) and it was easy.
The instrucions are ok but they've changed the design of the top damper mounting so instead of a clip holding it on it has a small bolt. It makes no mention of the torque setting for this and it could probably do with a washer as the damper hole is really close in size to the diameter of the bolt's head.
And the final annoyance, the cables don't stay inboard when pushing the tailgate back up so you have to locate them behind the slight indent in the tailgate metal which can only be done when you've lifted it up slightly. Not sure how to get around this and had me worried I'd assembled the cables incorrectly. Doesn't look like it judging by the photos and video clips I've seen.
*EDIT
Realised why it wasn't working, I'd missed out removing the black plastic wedges and now the cable retracts.