subwoofer installation

My gf has an 05 Elantra 5spd. I recently got her some subs to put in her car, but I am having a bit of a problem. I can't figure out how to get the amp power wire from the battery into her car. I can't find a grommet or hole anywhere on the firewall because it is pretty well covered up by the black matting. I have no problem drilling a hole and running the wire, but where can I drill it? It surprised me how well the car is put together and I can't seem to find a spot to drill that wont interfere wil something. Help! If anyone has put a system in there 05ish elantra and can tell me how they ran the amp wire I would greatly appreciate it.