no drilling. The rails were used factory rails that came with mounting hardware. The rubber/plastic track cap snaps out and there are threaded holes there for mounting. The plastic cap has to be cut with a hack saw where the mounts attach and the rest gets snapped back in. The directions also said you might have to remove the trim along the windshield, but I did not have to and am not sure why it would be needed.
I'll try to attach the instructions I used to this post. The instructions were a little different from the actual parts I ended up with, but they helped.