I installed 3 of 4 today (got talking to my neighbor and ran out of daylight to do the last one).
2 tips for install from my experience:
1 - plan on removing the rear wheels unless you feel comfortable doing some light disassembly and pulling of the rear bumper slightly to gain access to one of the screw points and you have a small offset screwdriver.
2 - I found that the supplied plastic insert supplied with the kit for the center attach point (rear flap) was not the greatest and it spun on me when I was attempting to drive the screw into it. Access behind the attach point is minimal (see #1). However, I had a couple extra screw clips with the hardware in my kit that I used to solve that issue. If you can gain access to the metal tab behind the plastic, then attach a screw clip there and the problem is solved. I gained access by removing the plastic trim clips underneath the rear bumper (3, I think) and the one at the very forward part of the rear bumper assembly, in the wheel opening lip, then gently pulling outward on the bumper assembly wheel opening at the top.
You will see what I mean when you examine the parts and directions, I think. I just finished the no drill TorkLift install, so I was not intimidated to loosen up the bumper. Didn't have to take off the rear light assembly to get enough room to reach the attachment point. Be careful to "layer" all the plastic correctly as you reassemble. Generally, the bumper assembly is on the outside of everything.
In a nutshell, the general idea of the installation is simple but the instructions are a bit complex. The idea is to put screw clips on 2 outer metal attach points (tabs) in the front (where the plastic trim clips used to be) and to make a vertical attach point from a horizontal one using an L bracket (for the bottom screw). The rear flap is attached with one outer screw clip attached to the plastic where a trim clip used to be, a bottom screw clip attached to the plastic with a new hole for the screw that you drill, and the center rear attach point as described above. Various spacers between the car and the flaps are used for proper positioning.
With screw clips at each attach point, I was able to install a rear flap without lifting the car or removing the wheel. The screws spin in most of the way with fingers, and the rest of the way with channel locks and an offset screwdriver.
These pictures are all from the front left install. I don't have any rear pictures but might post some tomorrow after I install the last one.
Pulling back the fender liner... I already installed 2 screw clips, the L bracket will be attached the the hole visible in the bottom center of the picture with a screw clip yet to be pushed onto the metal.
This is the bottom screw clip attached to the L bracket:
This is a picture looking up from under the car showing the L bracket attach screw and washer.
I have the top screw started and the mud flap will be rotated clockwise to match up with the holes...
All done except for the black plasti dip!