Just to give an idea on Cliffy installation, I was able to do the entire set in under an hour, but I didn't have to install the SIM card hole (that came installed from the factory). Here's what you need to do for each protector.
Left drop slot protector:
Simply remove the nut that attaches the right ramp to the upper post on the left sling. Lift the ramp up a bit and slip the protector into place. It's also a good time to change out your slingshot rubber if it's showing wear.
Right drop slot protector:
Same process as the left, just on the other side of the playfield. One nut to remove.
Like with any Stern, you will need to remove the apron. Everything will be straightforward here as you go. 5 minutes and you're set.
Skill shot slot protector:
You don't need to remove anything to install this protector, but it's easier if you remove the upper playfield. If you are going to be putting a protector on your phone scoop, you'll need to remove the upper playfield anyway. Might as well do it now and make life easier. The upper playfield is removed with only two screws. Both screws are small Philips heads and you can find one on the left middle part of the upper playfield. It goes down into the left pop bumper. The second screw is on the lower right part of the upper playfield, and it anchors into the lower right pop bumper. After removing these screws, you can move the upper playfield out of the way.
Once you move the upper playfield, it's easy to put the slot protector in place. Make sure the longer side is on the top side of the slot.
Phone scoop protector:
If you haven't already removed the upper playfield, check the skill shot slot protector to see how. You will need to remove the upper playfield as well as the phone from their anchors. The phone comes next, but it's just a couple of nuts that you can find on the left side of the phone. These two nuts go into posts, one is slightly larger than the other. After removing the nuts, lift the phone straight up to free it from the posts (make sure the phone's wiring isn't caught in the scoop, it should lift easily). Set the phone aside, being careful not to scratch the screen. You don't need to disconnect any wiring.
With the phone removed, you need to remove the two posts that are next to the scoop that have the rubber post sleeves. You ONLY need to remove these posts, don't remove the ones that have the rubber rings on them. To remove these posts, you need to remove a nut from the underside of the playfield for each one. When tilting the playfield up, make sure that the phone and mini playfield aren't swinging around. They'll hang just fine, but be gentle with how you lift and lower the playfield. Remove the nut from each post. Afterwards, each post can be carefully tapped from the bottom to be lifted from the topside.
With both posts removed, put the scoop slot in place. I find this easiest with the playfield in a vertical position so you can immediately put the two posts back in when the protector is in place. Don't force anything and risk bending the protector. If it doesn't lay flat, you don't have something aligned correctly. Put the two posts in, and slowly tighten the two nuts back on to secure the posts. Don't over tighten the posts or you can cause the protector to flex and it won't lay perfectly flat, and you can even damage your clearcoat. Snug plus a tiny extra turn is just enough.
Replace the phone first with the two nuts and then the mini playfield.
I played several games after and none of the protectors have changed how the game plays. Kickbacks can still hit the scoop and you can still make shots from the upper flipper to the SIM hole, the scoop, the ramp, or the targets with ease. The slot protectors don't seem to slow the ball down at all and don't alter play at all. Like everything else Cliffy makes, these protectors are top notch.