* you also need an enclosure built to spec for the subs - 3/4" MDF or 7-ply wood* you need a 4 awg or 1/0 amp wiring kit from a name brand
* you want split loom for power wire under the hood, and ideally the entire length for all cables
* a pack of black zip ties and zip tie mounts for securing wires in-place
* a board to mount the amp to and hardware to mount the amp to the vehicle. avoid mounting the amp to the box. the reasons are plentiful, trust me... just avoid it.
* a drill and drill bit for making a hole in the floor for grounding, masking tape for defining an area for sand paper for removing paint, and a bolt sized for the grounding ring terminal. make the hole just big enough to run the bolt through.
* a firewall grommet for passing the power wire through the fire wall - and a drill and drill bit (a hole saw bit or step-bit) for making a hole large enough for the 4 awg or 1/0 grommet
* silicone tube to seal the firewall and ground penetrations to the vehicle to inhibit water ingress and rust
* 4 awg or 1/0 ring terminals for your big 3 - 5/16" for most, but 1/4" for the alt positive
* i prefer to mount my amps and subs with t-nuts and machine screws - most reliable method since you can strip out wood screws
* best way to secure ring terminals to large power wire is with a tabletop butane torch and low melting point solder. otherwise, a vice can crimp the connectors.
* i use heat shrink for everything i can. you can buy kits with various sizes at hardware stores. most is 2:1 so buy it as close to the size you need as possible - this means buy a wide range.
