having done it both ways , drilling holes and applying them right on the surface angled
i found the best method is to cut them at an angle.. 45degrees and then apply them on the surface..
If you drill holes in the mask you will find that the quills stand straight out and not angled back as they should be.
kinda gives the mask a porcupine look instead of a hunter....
ohh and never burn a mask...the smell of burnt rubber latex is hard to get rid of
that's my story...and i'm sticking to it