Got my Mach1 Chin Spoiler in today......... :D

use drill bits the same size of a wee bit bigger than the shaft of the screws (should be self tapping machine screws)

Wow I surprsed that it doesn't tell you what bit to use. Drill one hole and see if the little push thing fits in it first beofre you do all of them. I'm sure you know this also, but hold the chin spoiler up with a ton of masking tape so it doesn't move when you find the desired position you want it in. Also if you make a mistake with drilling the holes too big or something you can always go to the hardware store and buy some nuts and bolts. Hope this helps and good luck. Post some pics, I want to see what mine will look like when I get it on Thursday(we have the same color stang).