I've heard that this can cause interference, but on my Civic, the battery is directly in line with my ecu, with the firewall in between. I've heard to run the wire away from the ecu, but this adds quite a bit of length to the line.

Is it really that big of a deal? I'm about to upgrade to 4 gauge, and I was hoping I can bring it through the firewall right behind the battery.

What should I do?

 

Try it. I didn't do it that way, but plenty of my friends have. They don't seem to have any problems.

 

it doesn't add any static to the system or anything? Or at least audible static?

 

don't worry about the ECU, it will be fine...