2008 Subaru WRX STi
Audio System Upgrade



  1. I didn’t want to replace the basic OEM head unit because I opted for the OEM Sirius Satellite Radio upgrade module when buying the car (transferring my lifetime subscription to it).
  2. I wanted to reduce the drone inside the passenger cabin that came from the cat-back installation.
  3. I didn’t want to work on my driveway during the current summer heat. It’s a typical August with 3 weeks of 100+° temperatures. In this case, it’s been a week of 104° or more and the 2 days of installation reached temps of 109° in the driveway.

Constraint 1: Retaining the OEM head unit and Sirius lifetime subscription
The OEM head doesn’t have a pre-amp out. Boosting signals out of the speaker wires also boosts the distortion that the OEM head has. Audio Control makes a solution for just these occasions. The LC6i (6 channel line conditioner) “accepts speaker level signals, both crossed-over and full range, and converts them to high-quality pre-amp signals.  Signals from factory radios with built-in crossovers can be overcome by summing them together, internally, to provide a full-range pre-amp signal.”

Constraint 2: Ambient road noise and cat-back drone
One word: Dynamat. Covering the floors and doors helps block outside noises and also adds insulation. A double whammy of win! Lining the rear subfloor (under the hatch cover where the spare tire and tools stow) addresses the sound that came up from the cat-back. Growl on the outside good. Drone on the inside bad.

Constraint 3: Installation
Installation was as easy as cracking open a checkbook at Car Toys of Hurst, TX. Jesse Caldera (sales) helped me brain storm the system. Juan Castillo installated all of the top-shelf gear that converts car power to music power.

Car Toys
810 NE Loop 820
Hurst, TX 76053

Equipment Details

Audio Control LC6i: Line Conditioning from OEM head unit

Alpine PDX-5 (discontinued): Power Amp

Focal 165V30 Speakers w/crossover (front)

Focal 165CA1
Speakers (rear)

JL Audio 10W3v3-4 Subwoofer (1 on the hatchback deck)


Installation Details

  1. Remove all the seats and carpet to get to the floorboards and the rear subfloor.
  2. Replace the OEM speaker wires (18 ga or 20 ga wire? Really?) with 14 ga to the doors and larger to the subwoofer.

  1. Remove the OEM speakers and the optional OEM subwoofer (too "boomy" IMO).


  1. Cover the world with Dynamat.

  1. Install the LC6i under the driver’s seat in place of the OEM subwoofer.

  1. Install an Alpine PDX-5 (discontinued) power amp under the front passenger seat.

  1. Replace the front & rear speakers with Focal 165V30/165CA1.


  1. Build a custom subwoofer box that clears the rear strut brace while being removable for when I need to load up the hatchback.
  2. Install a JL Audio 10W3v3-4 subwoofer into the custom enclosure. Note: The insert in the image below (side view) shows how Juan worked out the clearance for the strut brace and the close fitment to the back of the rear seat.



Performance? Excellent! Very clear, detailed highs and mids at all sound levels. Solid, tight bass without booming (again at all volume levels).

Appearance? Stealth baby! Everything went back together without a hint of change unless you look under the privacy curtain in the hatch to spy the subwoofer. Turn the ignition key and there’s no mistaking that someone’s waved a magic wand over the audio. Home run!



(C) 1995 - Present Mark Johnson