I was looking for a grommet in the firewall and I came upon the plastic piece and was just wondering if this removed to reveal a hole in the firewall I could use. If I can't use this, where would you recommend drilling through the firewall or a different grommet to run a 4Ga amp wire?

 

just cut a small X in the rubber to feed the wire through. If you want to be **** about it, when you are done, cover the opening with black silicone caulking.

 

Yeah, I just took my pocket knife and shoved it through... works great! No water!