I'm doing a budget build in my 4Runner. I am only concerned with sound quality and have a very limited budget for this project. It is also kind of a tinkering experiment. For any newbs reading this, you can achieve good sound quality on a budget. You just have to understand there are compromises. You also have to be willing to experiment and do more DIY fabrication. In my case, I'm using home audio drivers. Car audio drivers are generally designed with the environment in mind. The noise floor in a vehicle is much higher than the home listening environment. The acoustical properties of a car are also very detrimental to the audio system. Also moisture mitigation and mounting, etc... I'm going into this knowing I will not have the output levels that higher end car audio speakers have. I have no desire to compete, I just want my music to sound good. I can shoot for 90% of the sound quality but may only have half the output. In my case, that's fine since the OEM system has almost enough output, it just sucks doing it.
I tend to use things I have lying around and will also make many changes along the way so my initial speaker installations usually have temporary configurations until I decide exactly what I want. When it comes to aesthetics, I try to make things appear as stock as possible. As you'll see below, I care more about safe transfer of power than I do a flashy car audio fuse holder.
Disconnect the negative battery terminal before working on your system.
There is little to no room right next to the battery so I decided to make a mount using two factory threaded holes on the back side of the fender.
I dug through my miscellaneous screw bin and found some OEM bolts from another vehicle that fit the threaded holes. I also had a piece of plastic from another old project. After trimming to fit around a raised portion of the fender, it was perfect for this application.
For this build I used a Littlefuse mega fuse holder because I had one. They can also be found at some parts stores. https://www.amazon.com/FuseHolder
I don't use the pretty looking car audio fuse holders anymore. In my experience, the plastic becomes brittle over time and the covers of some are designed by kindergarten children. The covers either don't stay on or difficult to remove without breaking. I also don't like the set screw style connections under the hood. I'm sure there may be some nice expensive ones but I'm cheap. I've yet to have a problem with the two units I prefer.
This is another one I like. https://www.amazon.com/Blue-Sea-Systems-Safety-Block/
It is a marine grade unit and has a watertight compartment encasing the fuse. It also has a provision to carry a spare fuse.
I found some 1/4-20 Allen screws that fit the mounting tabs perfectly. I threaded the mounting plate for the screws. They do go through the plate far enough I may install some lock nuts on the bottom but so far they hold nicely.
For this install I used 4 gauge KnuKoncepts Kolossus Fleks Kable. I make my own connections using a hammer crimper in a vice. I keep an assortment of cable lug sizes around because I like them to fit around the screw as well as possible. I used two different sized lugs in this build so far. I tinned some copper battery cable ends before attaching them to the cable. I used heavy duty adhesive lined heat shrink at the ends of the cable. This was Tyco heat shrink you can get at Home Depot. Toyota uses flex loom and tends to wrap the entire length with electrical tape. I did the same. I usually make it match theirs but this time I was feeling bold so I used red.
The cable attached to the battery post perfectly and fit under the OEM post cover. You can see in these photos I routed the cable between the battery and power distribution module. Then it routes through the void in the fender. This is why I double wrap may cables. I make every attempt to ensure there are no sharp edges near the cable. Even so, make sure to inspect the outer shell for chaffing after a few miles and continue to inspect periodically after that. There is no protection between the battery and the fuse holder other than the steps you take to ensure a quality install.
The lugs in this fuse holder connect the cable directly to the fuse.
All Buttoned up.
Here you can see I also connected a small section of 4 gauge cable to the OEM ground on the fender. My system may only end up around 500 watts so I'm not really sure it will make a difference but its a good practice.