I just checked and it goes over the factory front valence. It's urethane but very sturdy; takes a lot of effort to flex. The sheet metal screws were not my doing, came on the car already installed. Will look up the Kamei one to compare.
I bought my car in October last year and have yet to find the make or model of this spoiler. I really like it, just curious as to what kind it is. I have never seen it on any other S30 before.