I've owned KSports for over two years now on a 60+mile per day daily driven NX....I like them quite a bit on my NX.
I know that makes me damn silly and somedody who doesn't know dick about suspension, but I still do...I say get them. Shoot Greg at Neverenoughauto.com an email & ask him what his best price is. I got a smokin deal that way, cheaper than the GB.
I drive a long curvy mtn road everday & the only other car to ever make me look silly in a bend was a guy who lives up the road from me that drives an Aston Martin Vanquish. Thats a good name for that car, yep.
I believe the first iteration for the B13 had weak seals and would leak. They've since gone w/another oil seal vendor and they seem to be fine now. I had to warranty one shock last year; the people in KSport USA were pleasant to deal with and I got a replacement quickly. I sent them a picture of the serial # taken w/my phone and they UPSed me one right out.
I've heard some bad warranty stories about the level of service from the supposed "recommended" suspension mfgs.
If you're not racing (as in, sanctioned events with a club or on a track), I would get them. They would be fine on a track, but if you're that committed you will want to spend more...Progress coilovers, for instance.
As Shawn so politely observed above, most everything you need is in one thread. Search around, READ, take your time buying what you believe will most suit your budget, needs.
Lots of people use KSports, I know the Mazda track guys like them...suspensions are very different for our cars, of course-speaking to the longeivity/ability to take abuse of the KSports only.
Spend some time
tuning whatever you get, and have a blast!!
Rob