I have seen many installed sets, as well as, installed many sets and owned trucks with factory bumper guards installed. I have also purchase NOS sets of factory bumper guards. The NOS bumper guards included the installation instructions in the NOS box. They are installed using the two existing bumper mounting holes at the left and right frame rails. They are attached from the backside, through the frame rail, through the bumper and into the bumper guard and into the spring nut in the bumper guard back brace. It is very clean and simple. I have seen them installed by drilling four extra holes in the bumper and this is not necessary.