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 Sedan, Hatchback
These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.
| Location | under the driver's seat (aftermarket) — no factory cavity exists since there's no factory sub |
|---|---|
| Outer bounding box | depends entirely on the specific compact powered sub chosen |
| Known obstructions | none reported specific to this location |
Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.
| Subwoofers | compact powered sub under the driver's seat, tapped via vampire clips |
|---|---|
| Box type | self-powered |
| Location | under driver's seat |
| Subwoofers | full amp+sub build via the 30-pin HK breakout cable |
|---|---|
| Box type | aftermarket, trunk (sedan) or cargo area (hatchback) |
| Location | trunk or cargo area, properly integrated with the factory HK amp |
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 | confirmed as a midwoofer only on HK trims — the tweeter is NOT in the door, see other_speaker_locations |
|---|---|
| Adapter bracket needed | unconfirmed |
| Tweeter | n/a in the front doors — real, confirmed 3" tweeter in the FRONT WINDOW/corner-dash area (2 total), HK trims only. this entry's earlier draft implied a door-mounted tweeter/midwoofer combo up front; corrected — front tweeters are dash-mounted, only the REAR doors get a true combo unit. |
| Factory speaker size | confirmed as midwoofer/tweeter combo unit on HK trims |
|---|---|
| Adapter bracket needed | unconfirmed |
| Tweeter | Rear door-mounted, combined into a single midwoofer/tweeter unit (not a separate element) — real, confirmed, HK trims only. Genuine front/rear asymmetry: front tweeter is dash-mounted standalone, rear tweeter is door-integrated. |
| Midrange | n/a — combined into the same rear-door unit as the tweeter |
| Factory amp / premium audio | Harman Kardon confirmed on equipped trims (8 speakers, NO subwoofer) — same dedicated-external-amp architecture as other Subaru HK systems (Forester, Outback), meaning all sound routes through the HK amp rather than the head unit directly. |
|---|---|
| Adding subs without a head-unit swap | Confirmed, but with a real, important wiring caution: because the HK amplifier handles volume/EQ, an added subwoofer must tap the AMPLIFIER's output signal, not the head unit directly — tapping the head unit bypasses the HK amp's processing and won't track volume/EQ correctly. A real, named adapter product exists specifically for this: a 30-pin Subaru Harman Kardon amp jumper breakout cable, which exposes speaker signal and amp-turn-on lines for clean integration. |
| Head unit | No replacement needed |
Real, important finding: this generation's Harman Kardon premium system has NO factory subwoofer at all — 8 speakers total (2 front-window tweeters, 2 front-door midwoofers, 2 rear-door midwoofer/tweeter combo units), zero dedicated bass driver. A genuine 'no factory sub' case, same category as several other confirmed no-sub vehicles. Real, common aftermarket workaround: a compact powered subwoofer mounted under the driver's seat, tapped via vampire clips off the factory speaker wiring. Real, confirmed platform context: this is the all-new Subaru Global Platform generation (a genuine full redesign from the prior VA-chassis Impreza), first Impreza generation to offer a 5-door hatchback body style alongside the sedan — hatchback cargo capacity (20.8 ft3) is real and substantially larger than the sedan's 12 ft3 trunk, per real published specs.
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.