Only precaution, you might want to make sure of what's on the inside where you plan to drill, I assume there's a crossover network board in there somewhere, so you might want to pull the driver out and take a peek inside first in any case.
"I realize that somebody playing free music isn't as commercial as a hamburger stand. But is it because you can eat a hamburger and hold it in your hand and you can't do that with music? Is it too free to control?" - Don Van Vliet (aka Captain Beefheart) discussing commercial success in the music biz