I want to be one more voice to the fact that all you may need to get rich bass and a full soundstage in a Model 3 with the premium soundsystem is to replace your lead-acid 12V battery with a lithium 12V.
After taking possession of my Model 3 Performance, I was pretty disappointed to find out that the coolest car on the planet had a pretty underwhelming sound system. Especially after reading the specs. Everything else about the Model 3 was so well thought-out and engineered, that I couldn't believe that the "premium soundsystem" on a $60k vehicle was pretty much lacking any low end, had a extremely forward soundstage, and overall sounded much worse than my Infiniti G37 that I owned before it. Sure, you can push the soundstage back, but it did nothing for the bass, and still sounded flat. No punch, no richness. Something had to be done.
A little about me: I do consider myself an audiophile. I have no relationship with any of the lithium battery replacement companies (I think Electriclove is affiliated with Ohmmu, for example). All I want is to share a fairly inexpensive, easy way to make the coolest car on the planet a little closer to perfection.
After reading several forums about the Model 3 bass issue, I was resigned to the fact that I needed to undertake this big aftermarket subwoofer project. Furthermore, it seemed that installing an amp and a new subwoofer was not lalone sufficient; after reading about the issues with the battery drain error messages, some sort of relay was required as well. I went online and bought all the supplies required. I was definitely gun-shy; I'm pretty technical, but I hadn't done one of these installs before.
I did notice that a few people here and there mentioned that a 12V lithium battery replacement alone fixed their bass issue. But of course this sounded odd. Why would it be that straightforward. After reading further in the forums, however, it seemed that replacing the battery with lithium might help avoid the dreaded "cannot maintain vehicle power" lockout after a subwoofer replacement, without needing the relay add-on. With the relay being the most intimidating part of the project for me (and with the least consensus about how to do it correctly in the forums), I committed to replacing the battery as part of the project. And hey, maybe those few forum posters are right, maybe that's all I would have to do?
Researching the lithium 12V options, it pretty much was either the afore-mentioned Ohmmu, or one other supplier, I believe it was Mountain Performance, though it seems they aren't selling them anymore. Ohmmu also made the bass improvement claim on their web page, albeit without any supporting data. I ended up going with Ohmmu, since it was less expensive overall (the mountain performance model needed an expensive steel add-on bracket to fit, whereas the Ohmmu was a drop-in replacement) and because they claim that their batteries have been used for years without the "cannot maintain vehicle power" problem if installed per their instructions. Plus, even if it didn't fix the problem, it would at least shave some pounds off the vehicle and increase its efficiency a bit.
The battery came and I installed it. I recommend using the written instructions, as the video is a bit outdated regarding the steps necessary to avoid the battery error messages.
I fired it up.
Wow. Bass.
It had punch. It was rich. You now feel the pedal vibrate with the beat. The soundstage was full and no longer forward-skewed. It was like the soundsystem sprung to life. Finally, it sounded as a premium system from a technically-obsessed car manufacturer should. And, six months in, I've had nothing in the way of error messages.
I returned all the other components. Amplifier and subwoofer replacement not required. Now, is this as good as a Reus upgrade? I'm sure not. But it's completely acceptable, whereas the stock sound was not. And, I was only out about $450. Plus, the car is lighter, and maybe there are some other advantages to having less voltage sag in the system.
Why does the battery fix the problem? I have no idea. Many of y'all with stereo installation knowledge would know better. Given that the rear speakers sounded more full after the replacement too, maybe the voltage sag from the 12V was starving the rear amplifier, and all the connected components? Either way, it works.
I hope this helps you, as it did me. Enjoy your bass!