Its actually a calmini lift that snake import. If you go onto the Frontier forum in the USA you will find heaps of info.
From what i have read they do crack the cross members on the kit itself, so allot of the guys who do actually use them off road weld in some extra gussets to strengthen them, then they are sweet.
You do know that you dont actually gain any extra travel, and that the rear has to have blocks put in to level the ute up.
The good thing is you can run bigger tires with no probs, the bad thing about that is, you put the D40's week drive train under more load and are way more likely to bust the front diff housing or diff itself, and it will effect your gearing, especially if you run 35's.
The good thing about all the extra hieght is not only the looks but the ramp over angle, aproach and departure angle is dramatically increased.
I think you can get them certified by an engineer to make them legal, BUT the cost can be huge becuase in some states you will have to have a lane change test done wich involves the hire of a runway, you can only immagine the cost of that plus the engineer plus all the paper work.
At the end of the day, as much as i would love the extra lift, it just doesnt seem worth it.
If you add up the total of the kit,fitting cost plus the cert to get it legal you are not far off the price of a SAS, i know its more but i would rather do that and turn the ute into a real beast that actually works awesome then soend all that money just for added ramp over extra.
Just my opinion.
Nath