First, its 4" height will cause severe drivetrain vibrations installed as is without the purchase of a fairly expensive SYE (slip yoke eliminator) kit and longer aftermarket CV driveshaft to reduce the driveshaft's u-joint angles steepened excessively by that height. Plan on another $500 or so for those two items that will also need to be installed by someone not afraid to open up the transfer case.
You could kinda-sorta get away without the SYE and longer CV driveshaft if you dropped the transfer case skidplate an inch with a spacer kit and installed a set of 1" taller motor mounts but that's definitely a second-rate solution.
That kit also includes a dropped Pitman arm which with the kit configured as is, definitely should NOT be installed. Installing it is 100% guaranteed to cause bump steer which is where the steering is forced left/right when you drive over bumps/dips in the road. On a bad bump or dip, the steering wheel can literally be bumped right out of your hands, hence the term "bump steer". The only time a dropped Pitman arm should ever be installed onto a TJ is when also installing a dropped upper trackbar mount, or perhaps for 6" or taller lifts. Don't let anyone talk you into installing it, dropped Pitman arms that are required on older CJ and YJ Jeeps are bad news for TJs 99% of the time.