The installation is pretty easy. You need to remove the wheels and the front extensions screw to existing locations and use a continuous adhesive rubber. The rear work the same way and you need to drill a hole in the rubber bumper (edge, not surface of body) to mount.
I guess it took maybe 1.5 hours total time including jacking car and removing wheels. I went super slow to be sure I got it right. I could do it under an hour now that I know how it works (directions are in Japanese, so really had to study the pictures).
Here's a picture of how much the wheel gap is closed on the front fender where the two part extensions meet. Also, my wheels poked a bit and this "flared" the fender nicely to meet the poke. They say it flares about 7 mm.