TEIN Flex for N15 are listed as VZ-R/JN15 set. Rear solid mounts are designed the same as stock ones in that they do restrict the stroke, but due to design (outlined below) the stroke of the shock is not an issue so the TEIN top mounts are fine.
TEIN Flex as described are valved and geared more towards track use, or for sporty handling, not quite as stiffly valved as the HA series (i have compared both). The Flex series are also setup like the D2 coilovers where when you lower it, you don't lose any stroke of the shock as the whole body of the shock absorber winds down into the mounting point, hence no stroke loss. Very good for getting cornerweighting done properly. Also the Flex series are often designed to be compatible with the EDFC (electronic damp force controller) which utilises small Servo motors attached to the top of the strut with a small controller for "finger tip" adjustment of the damping force from the drivers seat, plus the ability to set 3 different presets. A very trick setup....