Start with what is installed
Factory System Overview
The researched system has six speakers and an AM/FM receiver with cassette and six-disc CD functions. Some cars have a compact factory subwoofer enclosure beneath a front seat. That bass option needs to be considered separately from the door speakers; the overview does not identify a drop-in replacement driver for its enclosure.
Inspect before ordering
Record the model year, factory audio package and any previous modifications. Listen to every channel and note faults before taking the vehicle apart. A working baseline makes the final checks meaningful.
Guide coverage
2002–2004 WRX sedan only. Verify the actual 2004 door bracket. Source descriptions of the optional subwoofer seat position are inconsistent, so inspect the car instead of using seat position as a fitment rule.
Planning guide, not a fitment guarantee. Match wiring, impedance, adapters and removal procedures to the actual vehicle. Photos show selected configurations, not every trim or a complete removal sequence.
Radio Upgrade
Suitable single-DIN and double-DIN receivers can be installed using the factory mounting brackets. Keep those brackets and their screws with the car; a single-DIN installation also needs the appropriate kit.
Connections and clearance
Make secure insulated connections and leave service length without trapping cables. Check mounting stability, vents, switches and display clearance. A plug that fits physically does not prove amplifier or vehicle-function compatibility.
Test the complete system
Verify reception, source playback, balance, fade and any retained steering-wheel controls. Restore all required dash connections before powering the vehicle for a test, following vehicle safety procedures.
Radio access and integration
Suitable single-DIN and double-DIN receivers can be installed using the factory mounting brackets. Keep those brackets and their screws with the car; a single-DIN installation also needs the appropriate kit. Use a matching wiring harness rather than cutting the vehicle connector unnecessarily. Following battery reconnection, the parking lights may flash as part of the vehicle security behavior. Use the remote unlock function or the exact owner-manual override procedure instead of guessing at a reset. Test the new receiver and retained equipment before reinstalling the dash trim.
Before disassembly
Use the instructions for the exact vehicle and selected installation kit. Support removed trim and the receiver, retain fasteners by location, and stop if the wiring or dashboard differs from the documented configuration.
Shop Speaker Sizes
Browse verified collection categories, then confirm the actual installation requirements. These are not vehicle-specific fitment guarantees.
Front doors, 2002–2003 researched mounting
Browse by size; verify depth, mounting and electrical compatibility.Front tweeters
Browse by size; verify depth, mounting and electrical compatibility.Rear doors
Browse by size; verify depth, mounting and electrical compatibility.Speaker Upgrades
Check each mounting location separately. Nominal diameter alone does not establish depth, grille clearance, impedance or a suitable signal from the factory amplifier.
Front doors, 2002–2003 researched mounting
Factory: 6-1/2-inch
Replacement planning: 6-1/2-inch, 5-1/4-inch
Brackets required; maximum researched mounting depth is 2-3/16 inches.
Electrical note: 4 ohms
Front doors, 2004
Factory: 6-1/2-inch nominal
Replacement planning: Exact-bracket verified replacement
Inspect bracket variant; rear plastic cup may need trimming.
Front tweeters
Factory: 1-3/8-inch diameter, 13/16-inch height
Replacement planning: Custom-mounted tweeter
Custom bracket and wiring adaptation required.
Rear doors
Factory: 5-inch
Replacement planning: 4-inch, 5-inch
Use factory bracket and appropriate harness.
Optional under-seat subwoofer
Factory: Enclosed factory unit
Replacement planning: Measure for a complete replacement solution
No drop-in driver identified by the overview.
Access and mounting
The 2002–2003 front door speakers are 4-ohm units and use shallow mounting space. The source gives a depth limit of 2-3/16 inches; many aftermarket 6-1/2-inch speakers exceed it. Select a verified driver and bracket together, then check glass movement and panel clearance before final assembly. The 2004 mounting arrangement can differ, so inspect the actual bracket rather than relying only on model year or the presence of an optional subwoofer. Trimming the rear plastic cup may be required for a verified installation, but check what lies behind it before modifying anything. The small front tweeter measures approximately 1-3/8 inches across and 13/16 inch high. It needs a custom bracket and adapted wiring, not an assumed universal adapter. Rear doors use nominal 5-inch factory speakers; the overview supports suitable 4-inch or 5-inch replacements with the factory mounting bracket. Keep reusable hardware organized and test all speakers before closing the door panels.
Test before closing
Confirm polarity and each channel at a moderate level. Check window travel, latch operation and wiring clearance. Replace damaged clips and secure every panel without pinching its harness.
Tools
Panel tool; Phillips screwdriver; Vehicle-specific receiver kit and harness; Speaker brackets; Wire-connection tools; Depth-measuring tool
Electrical and restraint safety
Follow the vehicle battery-disconnection and restraint-system precautions. Do not probe airbag wiring. Keep the ignition off during connection work and protect exposed conductors.
Before cutting or drilling
Inspect both sides for wiring, glass, fuel lines and safety components. Stop if clearance cannot be verified. Protect cut edges, wear eye protection and restore seat and restraint hardware correctly.
Bass and Amplifier
The optional flat under-seat subwoofer can be retained with a suitable harness arrangement that provides its turn-on connection. The source does not identify an aftermarket driver that simply drops into the original box. For a replacement powered enclosure, measure under-seat space and check the full seat travel and wiring route. The overview provides no trunk enclosure dimensions, so a trunk-mounted solution requires measurements of the actual sedan rather than a borrowed fit claim.
Power and protection
Size cable, fusing and grounding for the equipment and run length. Protect the power cable close to its source, following the wiring system requirements. Route cables clear of sharp edges and moving hardware.
Final tuning
Start with conservative gain and crossover settings. Listen for distortion, rattles and missing channels. Check heat, charging-system behavior and unwanted key-off operation before considering the installation finished.
Installation Checklist
Work through the system in stages. Test before replacing trim, then repeat the checks after everything is secured.
- Record the exact vehicle year and audio package.
- Choose whether to retain or bypass the factory amplifier.
- Confirm radio kit, interface and antenna requirements.
- Measure speaker depth, opening and grille clearance.
- Plan safe wire routes, protection and equipment mounting.
- Gather tools and follow the vehicle's safety procedures.
- Label, connect, insulate and secure the wiring.
- Test every speaker channel at a moderate level.
- Check radio sources, phone audio and vehicle controls.
- Set gain and crossovers without audible distortion.
- Secure all trim, seats and safety-related hardware correctly.
- Recheck for rattles, heat and unwanted key-off operation.
Keep a record. Save the equipment models, interface instructions, wiring changes and tuning settings. Clear notes make future service easier and help another installer understand what has changed.
Car audio guides, upgrades and installation planning.
