What we researched for this specific generation: where an enclosure actually fits, what the factory speakers are, how the factory audio is wired, and which real builds and commercial products exist for it. Confidence badges say how well each figure is sourced — this is research, not manufacturer spec.
Body styles covered: 4-Door Subcompact Crossover/Wagon
These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.
| Location | rear tire well (factory Styrofoam bin location) or general cargo area |
|---|---|
| Outer bounding box | 5.75" mounting depth confirmed for at least one custom build. Vehicle-specific enclosure catalogues; published box footprints are lower bounds on the cavity, not the cavity: NET Audio '2020-up Kia Soul Sub Box Cargo Tray Sealed': 40 x 25 x 9 in (as printed; axes not labelled), 1.51 ft3, behind seat, under cargo tray, replaces factory storage bin. NET says the box downfires into the spare-tire well and the factory floor goes back on top; mounting depth 4-5/8 in (5-3/8 in with steel bump plates). |
| Known obstructions | Factory 8" subwoofer (see audio integration) is tucked in a location described by owners as a job 'for pros, semi-pros, wildly-optimistic amateurs, or serious masochists' — removing the far rear side panel is required to access it. |
Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.
| Subwoofers | 1x8" or 1x10" powered, rear tire well, reusing the factory Styrofoam-bin footprint (confirmed zero-visible-impact pattern) |
|---|---|
| Box type | sealed, zero-visible-impact |
| Location | rear tire well |
| Subwoofers | 1x12" custom, with plastic trays to preserve cargo room (documented owner approach) or dual-10" (Net Audio) |
|---|---|
| Box type | custom, cargo-preserving |
| Location | cargo area |
Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.
| Factory speaker size | 6.5" all around (this generation, confirmed via forum sourcing) — a genuine improvement over the PRIOR generation's odd, non-standard ~6.75" size, which required a baffle adapter to fit a standard 6.5" aftermarket speaker. |
|---|---|
| Known obstructions | None specifically documented |
| Adapter bracket needed | no (this generation); yes (prior generation, via baffle adapter) |
| Factory speaker size | 6.5" all around, same as front for this generation. |
|---|---|
| Known obstructions | None specifically documented |
| Adapter bracket needed | no |
| Tweeter | n/a — tweeter is dash mounted, front only |
| Factory amp / premium audio | Harman Kardon premium system (available trims, e.g. GT-Line): 10 speakers, 640W, driven by a 7-channel Harman Kardon amplifier mounted UNDER THE PASSENGER SEAT — a specific, unusual amp placement (not trunk-mounted) worth noting. Includes QuantumLogic Surround (QLS) and Clari-Fi processing, the same Harman-family technologies already confirmed on other vehicles covered here (Genesis Lexicon, also a Harman brand). Non-premium trims: factory 8" subwoofer, low-impedance (2-ohm) dual voice coil, non-standard cutout (uses only 4 of the standard aftermarket 8-hole bolt pattern, and the cutout itself is smaller than most aftermarket 8" subs) — a specific fitment trap for anyone assuming a generic 8" swap will bolt straight in. Kia's feature tables (2020, 2023, 2025): every trim has a 6-speaker system; the Harman Kardon Premium Audio "with center speaker, subwoofer and amplifier" is on the GT-Line only in 2020 (GT-Line 1.6T), optional on the GT-Line in 2023, and optional on the EX and GT-Line in 2025. CONFLICT: Kia lists a subwoofer only with Harman Kardon, which does not support the claim above that non-premium trims have a factory 8" 2-ohm sub (that forum thread may describe the Harman Kardon sub); Kia's tables also do not mention 10 speakers, 640W or an amplifier under the passenger seat. |
|---|---|
| Adding subs without a head-unit swap | Confirmed via forum discussion of upgrading the factory Harman Kardon subwoofer/amp — a documented, though technically involved, path. |
| Head unit | No replacement needed |
CONFIRMED ZERO-VISIBLE-IMPACT PATTERN — same family already extensively documented on the Nissan Rogue, Subaru Forester, and Mazda CX-50 : some owners place a subwoofer box in the rear tire well exactly where the factory Styrofoam bin was, sized off that Styrofoam bin's own dimensions, so the hard floor cover still goes back on and full cargo use is preserved. Specific alternative builds also confirmed: a Net Audio dual-10" subwoofer box, and a single custom 12" box built WITH plastic trays around it specifically to keep some cargo room rather than sacrificing it all — a deliberate volume-vs-cargo-space tradeoff choice documented by an actual owner, at a real 5.75" mounting depth.
RESOLVED 2026-07-19: Soul EV is a CONFIRMED spare-tire-well conflict — genuinely different from the 'safe EV' pattern already confirmed on the Genesis GV70 Electrified/Hyundai Kona Electric/Kia Niro EV elsewhere in this catalogue. On earlier EV model years, a battery HEATER fan occupies the spare wheel well, directly limiting spare-tire storage; 2020+ EV uses liquid cooling instead (removing the cooling-fan version of the obstruction), but owner sourcing confirms there is still NO room for a spare (compact or otherwise) on EV trims — the same constraint that applies to non-EV Souls per one source, though the EV's regen-braking configuration adds a further wrinkle: a gas-Soul donut spare CAN be used on a 2020 Soul EV, but only on the FRONT wheels — a rear flat requires moving the front donut to the rear and relocating that front wheel's tire to the rear position, a genuinely awkward real workaround. Treat Soul EV's rear cargo/spare area as a constraint, not confirmed safe, when planning a build near the spare-tire well specifically.
Outside links. Some are commercial products, some are owner builds posted on forums — the label says which. We do not endorse any of them.
Each link opens the tool with this vehicle already selected.
Measure your own vehicle. Trim levels, factory subwoofer options, and mid-generation changes all move these numbers, and a box cut to a researched figure that does not match your truck is wasted wood. Where a badge reads Unconfirmed, treat the value as a starting point for your own measurement, not as an answer.