From: http://caraudiomag.com/

Let me start off by saying that this is perhaps the single most challenging "simple" stealth fake floor install I have ever done, and I have done quite a few fake floors in my day.

The car in question is a 2011 Subaru STi Sedan, a new addition to the Subaru line up for the new year and in my opinion a fantastic re-imagining of the previous generation.

Here are two exterior shots of the vehicle, showing off its muscular bulging fenders and masculine lines:







The reason this install turned out to be extremely challenging was the combination of an oddly shaped trunk floor and a rising spare tire well, coupled with the need to fit a relatively large number of products while still maintaining an 100 percent OEM appearance. These factors certainly made for a lot of head scratching, and at times I felt like I was trying to force a round peg in a square hole.

Here are the goals for the system:

1. Achieve a good level of overall sound quality.
2. Obtain a classy, simple and elegant look throughout, with just a touch of flash.
3. Build a layout that result in ZERO loss of trunk space

Let us get started.

Here is the main power cable with its 150amp circuit breaker, 16 inches from the battery post.


The cable routes into the cabin via a stock grommet, sealed afterwards with silicone. I chose to run the power cable down the passenger side to keep it totally separate from the RCAs all the way to the back.


The signal starts with a Pioneer Avic-Z120BT double din navigation headunit, supplied by the customer:


As the car uses a JBL MS-8 for tuning, the remote display is mounted in the glovebox for easy access; an extension cable for the tuning microphone is also run to provide easy plug-n-tune from the front seat. The Pioneerís USB inputs are on the left side of the glovebox:


The unit's Bluetooth mic is installed at the bottom of the instrument cluster shroud:


While the GPS antenna is hidden below the cluster hood sitting on top of the gauge cluster unit itself.


This is the wiring harness bundle for the headunit, along with the Axxess steering wheel control module:


The Front stage consists of a set of Seas Lotus Reference 6.5" two way components. The tweeters are molded into the A pillar, wrapped in dash matching vinyl, and aimed off axis pushed as far forward as possible.


Here are a few quick build pics of the pillars.
Rings aimed and attached:


Grille cloth pulled, resin applied, cured, and reinforced from the inside with Duraglas/resin milkshake:


Body filler applied and sanded smooth:


Vinyl applied:


Tweeters wired up:


Installed into the pillars:


The back of the pillars:


Moving onto the doors; here are the four baffle spacer rings for the four doors, before and after being coated with spray on truck bed liner to protect them from the elements:




The front driver side door was sound proofed and new speaker wires run into the door:


The spacer ring baffle installed:


The Seas Lotus midbass wired up:


Midbass installed:




Almost three full sheets of Second Skin Deamplifier pro vibration damper went onto the plastic door card to prevent resonance and buzzing:


The passenger side front door received the identical treatment.
For the rear doors, the customer gave me a set of new Alpine Type R coaxials to act as rear surround fill processed by the MS-8. The rear doors received virtually the same treatment as the fronts, except I didn't quite go as overboard with the sound proofing on the door card:












The stock rear deck received a layer of Closed Cell Foam to prevent metal on plastic vibrations:


Here are a series of wiring pictures that show the bundles running from the front of the car to the back, ziptied and secured to stock loom every few inches; various wires cross over under the back seat so the correct wires are going to the correct side:














So thatís all the interior pictures; now itís time to move onto the heart of the install, and the part that gave me so many headaches.
For those of you unfamiliar with the trunk layout of the new Impreza Sedan, here is a picture of a stock trunk. As you can see, it is made up of three different sections, each at their own angle. This makes for a much tougher build when it comes to an OEM shaped fake floor build:


Complicating matters, the bottom floor pan of the spare tire well is also not flat, rather rising as it goes towards the front of the car. Two metal shields, which protect the emissions gear underneath, cuts into the space at the front of the well:


Now, the easy way to do a fake floor in this kind of trunk is to make the entire thing level with the highest point, which in this case is the front portion. This would result in a simple flat floor build with a ton of space underneath, especially towards the back. However, one of the primary requirements of the install is to sacrifice ZERO trunk space. The customer carries a golf bag in the car at all times which spans the width of the trunk, thus eliminating the possibility of a side fiberglass enclosure as well.

To top it all off, within this limited space under the stock floor height, we need to fit three amplifiers, two 10" subs, the MS8 and all the accompanying wiring and cables...yikes!
In the end, after much measuring, re-measuring, building, scraping, rebuilding and cursing, I did manage to pull it off. :) Here is the look with everything hidden.
As you can see, the trunk is 100 percent stock looking, the OEM cargo mat fits perfectly, and the entire trunk floor profile remained virtually unchanged:


Lift off the cargo mat and here is what you see. A brand new floor has been constructed out of MDF, wrapped in graphite synthetic Alcantara or street suede. Within the three-tired floor are two cutouts, protected by breathable grilles, wrapped in black trunk liner for durability:


Remove the covers and here is what you see. Luckily for me, the amplifiers supplied to me were the new Alpine PDX units, so three of them are stacked in a well towards the front, oriented at 23.6 degree angle (yes I know it exactly). A F6 sends 150 watts to each tweeter and rear fill speaker, another F6 sends 300 watts bridged to each Lotus midbass, and a M12 powers the subs with 1200 watts. You can also see the various cables for the amplifiers wind their way to the sidewall grommets, covered in carbon Techflex sleeving.
The subs in question are a pair of Seas L26roy 10" drivers; they reside in a 1.6 cubic foot sealed enclosure and are trimmed in their own shallow well. The interior of the wells are lined with black CF vinyl as chosen by the customer.




I also replaced the rather dinky trunk light with a high powered LED flood light; it is so bright that when I tried to take a picture of it, it looks like this:


The white LED flood light is designed to go with some subtle lighting effects inside the two wells. Flip a switch and the amps are lit up by edge lit plexi windows front and rear, while the subs have their own edge lit plexi pieces off to the side:


Of course, the whole point of the lighting is to see it at night. So here are some pictures of the trunk in a darkened garage:




All in all, this is a pretty simple looking install, but trying to sort out the stuff underneath was anything but simple and straightforward. Some of that complexity can be seen in these build pictures.
To start things off, the L26roy ideally wants .8ft^3 each sealed, so I measured out that volume with Styrofoam peanuts:


And poured two boxfuls into the spare tire well to get an idea how the enclosure need to be constructed:


Next, the spare tire down point was cut and removed from the vehicle:


And the well was covered in a layer of Deamplifier pro:


Next, the area was taped off, and the desired borders of the sub box marked:


Eight layers of fiberglass mat and 6 layers of fiberglass cloth were used, and when that cured, the bottom mold of the sub enclosure was pulled out:


It was then trimmed to the desired shape and size:


Next a top baffle was mated to the bottom mold with industrial strength epoxy:


Fleece was stretched from the bottom mold and stapled to the rabbeted edge of the top baffle, and resin applied.


When this cured, I reinforced the enclosure from the inside with ten layers of mat and sealed everything off with about a gallon of Duraglas/resin milkshake:


Next, the walls for the subwoofer well were secured:


And the entire top surface was wrapped in black CF vinyl:


The edge lit Plexiglas strips were then screwed down, and the outside edges received a strip of white LEDs:


The plexi and LEDs were then covered with black duct tape to prevent light "leakage", and the wires were secured and run to their desired locations:


The sub box is now complete and bolted to the car with two HD bolts:


Next is the build of the amp rack, the bottom of the rack had to orient itself with the rising profile of the bottom floor pan, while the top edge had to be at the precise angle of the top floor to give the fake floor panels proper support.
After about half a dozen or so aborted attempts, these are the finalized pieces, before and after application of black CF vinyl:




Next the rack was assembled:




And the stack of amps test fitted:


Then the edge lit plexi window pieces and their LED trips were attached to the front and the back:


And sealed with black duct tape:


Next, each amplifier was wired up, and then secured to the amp rack, with all the cables carefully routed to the side wall grommets, following generally the same curvature:




Next, all the wires on the outside of the rack was bundled and secured:




This is the little piece that supports the MS8 at the front of the trunk. The two brackets line up to existing OEM bolts:


Then, everything was installed into the trunk, all the wires properly secured and organized. This alone took about a day and a half to figure out; as I had to give everything enough room for quick trouble shooting and tuning. All the essential wires are on distribution blocks and barrier strips, with identification labels written on the MDF next to them:






Quick picture of the termination of the L26roy subs:


Finally, the top fake floor pieces were cut and test fitted:


The back two sections were jointed together forming one continuous piece, and the cutouts made. What looks like a rabbeted edge is actually another smaller cutout made out of 1/8" hardboard:


The grilles were then fabricated:


And test fitted:


Next the floor was wrapped in Alcantara:


Here are the 1/8" hardboard "rabbeted edge" I was talking about, they were also wrapped in street suede:




And mated to the main floor pieces with a combination of HD epoxy and staples:


Here are the grilles pieces, with metal mesh secured, and then wrapped in black trunk liner:




The front portion of the floor is its own separate piece; here it is before and after suede:




Same goes for the side pieces:





Okay, thatís it! Overall the car sounds quite nice. Tonality is nice smooth and balanced, stage height is good, as is width; depth is above average and there is a pretty decent center image. Though without a center channel, I feel that perhaps a more precise center can be achieved with a tune-your-own processor instead of the MS-8. The car went on to compete at the MECA SQ event in Sacramento, and had a very respectable showing, placing third in class and less than a point behind the class winner and just a quarter point behind 2nd place! (Which was the Lexus IS-F I worked on last year.)



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