4. The premise of all IFS GM lift kits over 4 inches is to lower the mounting points for both the upper and lower A-arms. This is always done with some form of new subframe that bolts in where the lower A-arms were mounted from the factory. In the case of this Explorer Pro-Comp kit, the rear piece (of the two-piece) subframe bolts in with the stock lower A-arm bolts and with six new bolts that must have holes drilled where the bumpstop we just cut off were located. The directions provide you with an idea of where the holes will be, but Corder used the new subframe as a template to make sure he got it dead-on.