Thx for the link, I took a look at that DIY. Personally, I think that these sliders on the 250 are useless for anything other than a parking-lot zero-mph drop, and maybe not even for that. Any lateral torque whatsoever on the slider and it will bend immediately, and will likely rip the engine mount bolt & its mount as well. A bike sliding on its side at even moderate speeds, even one as light as ours, is still 400 lbs of inertia moving at speed, and there's no way that long thin bar stands up to that force without failing one way or another, and hopefully not damaging anything other than itself.
That said, I do like them cosmetically, it is nice to not have to chop up the fairings, and they give the bike a more aggressive look. But I think that we ninjette owners are kind of stuck, as the aggressive fairing design is much wider off of the frame and engine of the bike compared to other supersport bikes, making the distance that a frame slider mount needs to travel longer than on other bikes.
Look at how sliders mount on an R6, for example:
No long bolt, the mount of the slider itself snugs up against the frame, holding it in place against lateral torque.