I've never been impressed by Kelderman if we are being honest. Every truck I've ridden in with their rear air ride kit has bunny hopped at odd MPH, and hasn't driven that nice.
I remember one of their 450 customers brought me one from Kansas City MO, complaining the truck had weird tendencies. 24's, Pirellis, and their stock height kit.
Without 1000+ lbs in the bed, the thing would hop and skip from 30-45, and then from 55-60 again.
It was annoying as sin to drive in traffic, at 70MPH, it was fine.
He ended up selling the truck because he was so disgusted with it.
They are notorious for blowing a product out to market right away, without necessarily spending a lot of time worrying about the geometry of things, or how it will actually work in a real world situation. But it looks cool, and its always there, so they will sell product I suppose.
Just my .02 cents on it
Jared