Though the product is good - I did not trust the clips and that came with the hardware kit and installed #8 U-nuts instead, yes you will need to drill holes in the fender for this. Installation was challenging and difficult to get the flare to line up with the underside fender edge... you really need to push very hard. I overcame this with an Irwin 6" Quick Grip clamp - once you set it with the lower screws (do not tighten), the top most screw is installed first, the installation goes easier. I also had to use a plastic body tool and some dawn soap water to align the rubber seal against the body to even it out and seated properly. Definitely not for a novice to install. You can get the U-nuts at any hardware or auto parts store. You can also get replacements from Bushwacker but they will take 4 weeks to arrive - not so customer friendly as for as timeliness.