JL Audio Stealthbox® Custom-fit fiberglass enclosure with 12" TW3-D4 subwoofer — fits 2015-up Ford Mustang coupe - $800
Local pickup in the Springfield Missouri area.
Can send more pictures upon request.
I hope I'm not beating any dead horses here. I have an '18 GT with the standard (non-active) exhaust. Generally speaking, the sound is pleasing with no drone. What I would like is a very deep sound with no drone and no raspyness. Like some have stated, deep sound at idle, nice quiet...