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1 September 2026: Don't Ground Your Sub to the SN95 Lower Frame Rail

Project Status

Current Stage:

3: Subwoofer

Budget Spent:

$1353.50/$4000

Next Milestone:

Cabin Audio

BUILD OVERVIEW
PARTS LIST

I read online that it would be a good idea to ground my high-power car audio system underneath the sway bar bracket on the lower frame rail of my SN95. This would end up being the worst decision of the build thus far.

First, an update:

~Timelapse of Skar Negative Battery Terminal Install~

We installed the battery terminals first. We found that there weren’t enough ports for the stock power wires on the positive Skar terminal, so we ordered a set of 6-way zero gauge terminals. 

~Timelapse of Positive Battery Terminal Install~

We may end up using the other set of mismatched terminals on the rear lithium bank.

~Keeping the Kitty Out of the Engine Bay~

Throughout the wiring process we had to actively repel our neighbor’s cat from the engine bay. She always wants to be where she can’t go. 

~Fusing the Main Zero Gauge Power Wire~

Running the main power wire wasn’t too bad. We ran it through the stock wire grommet on the driver’s side. Made an X-cut and ran it through with a wire hanger lead. Unfortunately, since the Knukonceptz wire is oversized, the zero gauge wire will not fit in the terminals with ferrules on. I may end up soldering the ends.

~Full-Pan Shot of the Main Zero Gauge Power Wire~

~Realizing the RCA Cable is Running the Wrong Way~

After running the power and RCA lines, we realized that the RCA cable is directional. We didn’t know RCA cables could be directional. So we had to rip that out and flip it. Later, we had to add the remote line that we forgot to run with the RCA cable. So we’ve now done wire runs front-to-back four times. 

~Beauty Shot of the Subwoofer Wiring~

Next we wired the dual 2-0hm SA-12 v.3 subwoofer down to 1 Ohm…

~Dropping the Sundown Subwoofer in the Box~

…and dropped it in the box.

This video caused all kinds of discussion on TikTok. Some people kindly pointed out that we could have used pilot holes or bolts and inserts rather than screws. Some were not so kind about this. Some people said there are special tools for this task (why would we use those when we have a bucket?). Never knew there would be so much passion about a bucket. 

The only part that really peeves me is that someone laughed at me in the comments for having “female fingernails.” I intentionally have long, healthy fingernails. I am genderfluid. Honestly, the comment comes across as a compliment to my ego. But I don’t like the idea that femininity has no place in car audio. That makes me feel excluded. 

~Timelapse of the Big 3 Power Upgrade~

Then we did the Big 3 upgrade: alternator positive fused to battery positive, engine block (alternator mounting bracket) to chassis ground (sway bar mounting bracket), and battery negative to chassis ground (sway bar mounting bracket).

~Beauty Shot of the Engine Bay with all the Infrastructure Installed~

I think it turned out looking pretty nice and clean.

~The Amplifier Rack on the Back of the Back Seats~

Next, we moved to the amplifier rack. The further we get into this project, the more concerned I become that we will not have enough space on the amp rack. We may have to turn to angling the amps and DSP upward or stacking them vertically.

Why we moved to the amp rack before putting the sub in the trunk? I have no idea. We knew the sub box would never fit in the trunk through the regular opening. Doing the amp rack first forced us to lift the sub enclosure over the amp rack and through the back seat hole. Nonetheless, the sub made it in without catastrophe.

You can see in the second image that we had to bend the metal plate that the back seats bolt into to make enough space for the 13.5″ tall box. 

~Partial System Walkaround~

With everything installed and subwoofer ratchet-strapped, it was time for an oscilloscope tune and a proper test. 

~The Subwoofer Rattling Objects off of my Car~

We got it working!

For about 30 minutes.

That brings us to the point of the title of this post. After initial testing, we drove to my dad’s place close-by. We listened to exactly 1 song: The Edgar Winter Group – Frankenstein. Right at the end of the song, the Mustang shut off. We all looked at it for a moment confused, until smoke started to escape from under the hood. We popped the hood and grabbed the fire extinguisher – luckily we didn’t need it. 

Evidently, the ground at the sway bar bracket on the lower frame rail came loose on the short drive, and all the power in the system tried to ground itself through the tiny 10 gauge ground wires for the fuse box. Those wires turned to liquid, and the insulation to fire. 

We had to get a fuse box from a junkyard Mustang, and replace it one little tiny wire at a time. 

~Aftermath of the Fire~

~Newly Grounded to the Strut Tower~

To ensure this doesn’t happen again, we grounded to the strut tower instead of the sway bar bracket.

~Installing the Stealth Bass Knob~

Finally, we installed the bass knob inside the center console. I don’t want anyone walking by my parked car to be able to tell that there’s nearly $400 of copper wire inside. Then, we tested again.

~Subwoofer Bumpin’~

I’m elated with how it sounds. So freakin’ clean. Will post more videos of the system pumping soon.