Essentially, if you are planning on exploring the vast world of Los Santos at all, then this mod is indispensable (and a reminder of why the PC version of GTA5 is, indeed, the best one). In addition, it adds elevators to get you into the top floors of the FIB building and markers to help you find all of the explorable interiors. Madrazo’s ranch (doors open, but R* put an invisible wall there :\ ).