Just letting you guys know, you don't really have to use tapping screw for those plastic parts, you can still use the regular screws.
If you clean up your car a lot, those tapping screw will start to lose some grip on the plastic part after a while. I remember reading some article some where that it says, if the tapping started to losing grip on the plastic parts, just use the regular screw (machine threaded?), and it will grip to the plastic better.