Anyone know where I can get an amp power cable through the firewall on a 99 a4?

best bet is through the ecu box and the hole in the firewall.
 

do a search on this dite and you will find the information on how to do it.

Running an amp cable...long
 

I have heard of interference through near ECU...

I recently ran mine through the firewall. The location I used was a large multi-grommet just to the left of the steering column.

1. Remove lower dash first, and you will see the large grommet, rectangular in shape, with a few extra holes. I used one in the far right side of the grommet. I was able to push a 4 gauge through without difficulty.

2. The cable will actually be under the car, near the steering arms. I actually went under the car to make sure the cable would not interfere with the steering, etc.

3. Once clear of the steering, I secured it with a few nylon ties.

4. I then came up the front of the battery tub, or what ever it is called, on the driver's side. There should be any extra grommet location sharing the vacuum line for the brake master cylinder. I slid the cable through and was then able to attach it directly to a fuse block on the battery.

5. Inside the car..I pulled the driver's side kick panel and then door sill trim and ran it to the trunk.

I am still in the process of adding my other components, so I will let you guys know how it all works out.

Re: Anyone know where I can get an amp power cable through the firewall on a 99 a4?
 

I put "0" guage through the hood release gromet on the drivers side. Saves you two feet of VERY costly cable.

How do you get through the hood release gromet? Isn't there a plug there?

thanks for the write up!! i'm gonna be doing this soon too

I did mine through ECU box
 

After moving ECU out of the way, you'll see the footlight through the hole if you open the driver side door. Tie the cable to a coathanger wire and push it to the left of the footlight. Then, put your hand behind the plastic cover above the foot pedals from the right side, grab the wire and pull it out.