Some tips: All the power cable under the hood should be sealed up watertight. That looks like 4 gauge cable, but the fuse holder looks like it's sized for 1/0. I'd replace that fuse holder for one sized for 4 ga so the o-rings will seal against it. Use a 60A fuse if its CCA wire. Use an 80A fuse if it's copper. No higher. I'd also get some 3:1 heatshrink with the glue lining and put over that copper lug. Seal off the exposed wire by the lug. If that wire is CCA it's prone to corrosion. Keeping it sealed and watertight will make it last longer and prevent issues. Make sure to put some rtv silicone on both sides of the rubber firewall grommet. Maybe add zipties to both sides so it can't move. Add zipties to the power cable under the hood so it can't move or rub against anything. Keep it clear of the exhaust or anything that gets really hot. Maybe add a washer to the positive battery bolt so your getting better electrical contact. Make sure the negative lug in the trunk had all the paint scrapped away so its making good electrical contact. Let me know if you have any questions about wiring the subs together or amp/headunit settings. Take it easy. 👍