Same for me, I head to lean up underneath the dash on the drivers side. I was attempting to drill out a hole at like a 45 degree angle, which is next to impossible especially without a punch. Well I found a small dented spot in the firewall, so I was able to get the bit to grab, as soon as the bit made it through the hole saw just ripped the ***** apart.
But then I had to have another hole next to it for the other run of 1/0. But there was no other small dents in the firewall to drill on. I basically just stuck the bit of the hole saw in the existing hole, pushed it to the top and let that ***** bite a little bit and it ripped right through.
Didnt turn out how I expected because I wanted to have two purdy holes with grommets but it ended up working out okay. I dont think it will have any problems, its caulked all to hell and the wires arent going anywhere. Zip tied and sealed up tight //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif