I would suggest not drilling any holes to install the side scoops. Mine are Ford side scoops, the same as on the Calf. special, and I used only the included double sided tape for the install. My body shop tech said the tape will hold them on without any problems and his years of experience proved true. They have been on for plus 6 months and two trips to Fla. He felt that if for some reason I wanted to go back to the stock look, I could do so without an issue of covering holes. Bottom line, don't bother drilling holes!