No experience with them but they do have pretty stiff spring rates at 10 kg/mm front & 12 kg/mm rear (or 560 lbs/inch front & 670 lbs/in rear). That's almost twice the stiffness of the KW Variant 3s which are 350 lbs/in (which most consider the "Gold Standard" of NSX suspensions).
Also, seen a lot of people talking about
BC Racing Coilovers on Prime. Might want to consider them as they are in the same price range as the ARK ST-Ps.
http://www.nsxprime.com/forum/showthread.php/159029-BC-Racing-Coilovers-Comprehensive-Review