So the price for a good 0 awg ofc cable starts around 6-7k a meter. The reason why I did this was because I'm building a sq setup in this car with multiple amps, dsp and a Capacitor. However, you don't just do the big3/4 when installing a Audio setup. But here's the differance what I experienced
Voltage at battery with stock wiring & engine running:
~13.48V
Voltage at battery with stock wiring, engine running & main lights, interior lights and ac turned on:
~12.32V
The same test after the big4
~ 14.3V
~14.1-13.9
Tests were performed with the engine warmed up and using a dmm. My car still has the factory wet cell battery which is more than 5 years old too
Here's a link to why Big3/4 are really helpful
https://blog.down4soundshop.com/why-big-3-upgrade/