2020-2025 Kia Soul 3rd Gen — subwoofer box fitment

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

Where a box actually fits

These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.

Standard Likely

Locationrear tire well (factory Styrofoam bin location) or general cargo area
Outer bounding box5.75" mounting depth confirmed for at least one real custom build.
Known obstructionsFactory 8" subwoofer (see audio_integration) is tucked in a location described by real 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, a genuinely difficult factory location worth flagging clearly rather than understating.

Starting points

Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.

Budget

Subwoofers1x8" or 1x10" powered, rear tire well, reusing the factory Styrofoam-bin footprint (real, confirmed zero-visible-impact pattern)
Box typesealed, zero-visible-impact
Locationrear tire well

Enthusiast

Subwoofers1x12" custom, with plastic trays to preserve cargo room (real documented owner approach) or dual-10" (Net Audio)
Box typecustom, cargo-preserving
Locationcargo area

Door speaker fitment

Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.

Front doors Likely

Factory speaker size6.5" all around (this generation, confirmed via real 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 obstructionsNone specifically documented
Adapter bracket neededno (this generation); yes (prior generation, via baffle adapter)

Rear doors Likely

Factory speaker size6.5" all around, same as front for this generation.
Known obstructionsNone specifically documented
Adapter bracket neededno
Tweetern/a — tweeter is dash mounted, front only

Factory audio integration

Factory amp / premium audioHarman 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 real, 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 real, specific fitment trap for anyone assuming a generic 8" swap will bolt straight in.
Adding subs without a head-unit swapConfirmed via real forum discussion of upgrading the factory Harman Kardon subwoofer/amp — a documented, though technically involved, path.
Head unitNo replacement needed

Known integration products

Mounting locations

Standard Likely

REAL, 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. Real, 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 real, deliberate volume-vs-cargo-space tradeoff choice documented by an actual owner, at a real 5.75" mounting depth.

Builds and products found for this vehicle

Outside links. Some are commercial products, some are owner builds posted on forums — the label says which. We do not endorse any of them.

Build it for this vehicle

Each link opens the tool with this vehicle already selected.

Before you cut anything

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.