2017 Mazda 3 hatchback DIY sub install, without cutting/splicing into factory wires. It sounds so good in this car. Should I post how I did it? : r/mazda3
2014 - 2018 Mazda 3 Amp and Sub Install - YouTube
Mazda 3 Sub & Amp Install - YouTube
JL Audio Stealthbox® Custom-fit fiberglass enclosure with 10" W3v3-2 subwoofer — fits 2004-09 Mazda 3 hatchback at Crutchfield
Mazda 3 Sedan 2008 - 2013 12inch sub Fibreglass subwoofer box - premium sound | eBay