Where to get the cable through for my Audi A4 B7

I need to wire a 50mm2 cable from my battery in the engine bay to a battery in the back to power my subwoofers. The cable I have now barely fits through the hole behind the glove box, and it’s only 16mm2. Is there another hole that I can use, or do I need to drill one? Any advice would be appreciated.

You might want to check under the driver’s side. There’s often a grommet that you can use to run cables through without drilling.

If you do end up needing to drill, make sure to use a grommet after to protect the cable from the metal edges.

You could also look into running it along the side of the car. Sometimes that’s a cleaner way to do it without drilling.

Make sure to check your local laws about wire sizes and routing. Sometimes there are regulations to follow.

I’ve heard that some people use the existing wiring harness holes. You might find enough space if you do a bit of maneuvering.