I installed the Vortex Rammer air box and Power Duct at the same time...just 3-4 days ago. Overall the install was easy, but I've been turning wrenches for a decade or so.
If you're handy with tools at all, you'll have it on in very little time.
The stock duct should pop out with a little effort (it is held to the radiator shroud by some plastic "nipples" inside rubber grommets). This takes a little prying, but you will not break it.
Installation requires you to attach the silicone hose to the backside of the MAF meter (this may honestly be easier to do off the car...its a very tight fit) and then slide the silicone hose onto the TB with the duct already attached to the MAF meter.
They should have supplied you with most of the clamps, but if not you can certainly reuse the hose clamps on the stock ducting. In fact, I know I used the stock clamp that connects the duct to the TB.