alright, im gonna give a quick cover of all the basis. Ive read every post, im gonna tie all of them together.
Anyone who disagrees, feel free to discuss with me. Im still learning, but this is all the information ive read, gathered, tested, and seen to be true from my experiences.
first of all, soldering makes a solid connection, but solder can add resistance to the connection. Id recommend a solid crimp over solder any day.
alt: you could have a 5,000A alt, but if you dont have the batteries to support it, its useless. Amps dont draw directly from the alt, they draw from the batteries. If you dont have the batteries, the alt is not exactly useless, but exponentially less helpful. add to the yellowtop....or scrap it and go with new, dry cell batts (kinetik, xs, shuriken, ect)
You need the wire to support the current from the alt to the bat. Big 3 is essential.
Good connections....obviously another essential.
Amp grounding at frame:
Your frame may be a bad ground. Sedans seem to have worse grounding to the frame that many other cars because all the welds in it. When you ground to the frame, your purpose is to connect the ground from the batt to the ground from the amp thru the frame. Running a 0g wire between the 2 bypasses the resistance added from the frame welds. 0G cca run of about 50 feet, according to my last measurement had a .06 ohm resistance. Thru the frame on my sedan was so terrible that I couldnt even get a steady #. Something to think about, maybe test in your car.
this being said, I cannot reason the concept of why we should shorten the ground to the frame. Maybe someone can explain why the amp ground needs to be so short (36" max) if a 36" run 0g ground has virtually no resistance. Even if it heats up, the impedance would be super low. In my reasoning, wouldn't it be better to ground to the battery, and bypass the frame welds? The frame is what Ive tested to show high resistance to the front, not the wire.
Hope this helps you, man!