Hmmm ... I'm not one who knows much about mounting sideskirts ...
The vertex ones fitted to the AE86 in the pictures was a quick job - the car was brought to the drift track and Ken Streeter had only about 20 mins to fit the kit before it went out. There are more mounting points / bolts to go on however this was all done in a hurry in order to get the car on the track in time with the bodykit on it.
I believe that the whole kit has now been fitted properly including the front bar however pics are yet to become available.
Ken's OEM ones are two piece to simplify the manufacturing process however they are copies off genuine OEM sideskirts which came off the green Option 1 Garage coupe from Japan. When installed and painted, you wouldn't be able to tell the difference. Rather than just copy them straight, I believe that he has improved the process by cutting down on the number of parts.