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MTX Audio Thunderform FMUST05BK12U (Black, Unloaded)

Ford Mustang 2005-2009 Unloaded 12" Fiberglass Subwoofer Enclosure

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MTX Audio Thunderform FMUST05BK12U (Black, Unloaded)

Ford Mustang 2005-2009 Unloaded 12" Fiberglass Subwoofer Enclosure


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General Features:

  • Unloaded 12" Fiberglass Subwoofer Enclosure
  • Fiberglass Construction
  • Fits in Ford Ford Mustang 2005-2009
  • Color: Black
  • Fits single 12" subwoofer
  • Enclosure Volume: 1.2 Cubic ft
  • Dimensions: 15-1/8"D x 27"L x 14"H

Subwoofer Specifications

Subwoofer Size
Refers to the diameter of the subwoofer, measured in inches.
Subwoofer Design
This is the design of the subwoofer or the opening of the subwoofer enclosure. Each design has it's own benefits, whether it is a square, circle, or oval.

Round/Circle: This is the typical and common subwoofer design. They have a round cone and are a circle in design.

Square: These woofers are able to achieve a greater cone area in a smaller space. Because of the greater surface area, some square subwoofers will be louder than a round subwoofer of the same size.

Round / Circle

Enclosure Specifications

Box Type
Represents the style of the enclosure. Be sure to purchase the appropriate enclosure type and internal volume that will be compatible with your subwoofer's recommendation.

Sealed - Sealed boxes are those that have no holes or vents in it. The only hole in a sealed box is where the subwoofer is installed. Smaller sealed boxes require more power than a larger sealed box. They provide a tight, accurate bass, while the larger sealed enclosures provide a "boomier" and louder bass.

Ported / Vented - Ported/Vented Enclosures provide an even boomier, louder bass, but less accurate then a small, sealed box. Ported enclosures typically require more airspace per sub and also less power output from an amplifier to perform correctly.

Bandpass - Bandpass enclosures make subwoofers perform efficiently, but loose. The bass is not as "boomy" as a ported enclosure nor as punchy as a sealed enclosure. Bandpass enclosures work well with lower to mid-level subwoofers.
Number of Subs/Speakers
This value represents the number of speakers or subwoofers that the enclosure accommodates.
Box Style/Shape
The box style or shape refers to the actual shape of the box. Square and rectangular boxes are straight-edged boxes on all sides, whereas hatchback and truck style enclosures feature an angled front or back design that allows for installation in places short on depth such as single cab pickup trucks. You can also use such enclosures in hatchback cars or other vehicles where space is a premium. Tube and cylinder shaped boxes were made popular by Bazooka and are a great option for those looking for a nice amount of bass without sacrificing lots of space. They may even fit in locations that slim truck boxes cannot fit in. If the enclosure is vehicle specific, we encourage you to read the product description to find out which vehicles the enclosure is made for.
Vehicle Specific
The height of the item, measured from top to bottom, in inches.
The width of the item from left to right (side-to-side) measured in inches.
The front-to-rear depth of the item, in inches. If the item is angled or slanted, this value is the bottom measurement.
Number of Terminals
The number of terminals the enclosure has. Each terminal represents 1 positive and 1 negative.
Box Exterior Color
The color of the enclosure's exterior/outer finish.
Box Finish
The material used on the outside of the box. Most boxes are carpeted to prevent exterior scratches; however vinyl is popular as it can often be color-matched to a near exact look of your leather factory interior.
Type of Enclosure
Some of our Vehicle Specific enclosures are loaded with a subwoofer and an amplifier, some are only loaded with a subwoofer, while some are empty boxes.
Compatible Vehicle Make and Model
The model of vehicle that this vehicle specific product is designed for. Please keep in mind that engine variations can affect the compatibility of the products.
Ford Mustang

Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
4 Star
3 Star
2 Star
1 Star

Average Attribution Rating


Colorado Springs, CO

Pay the extra money and get the JL Audio Stealthbox

October 23, 2012

I would not recommend this box to anyone. I don't believe the box provices the air space it claims, and neither does the professional shop where I had it installed. The box is flemsy, and it does not fit securely into the car. I've had another MTX Thunderform box in the past that I loved, but this one is no good. I actually gave this box away. Do yourself a favor and use that money to start saving to get a JL Audio Stealthbox. You will be much happier. I know I am.

7 of 8 found this helpful

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Cincinnati, OH

Nice enclosure.

August 30, 2011

I have had this installed 5 months now and LOVE it. It tucks tightly into the right (passenger) side trunk in what was pretty much unused space. Put a 12" Kicker DVC in there and with my 400 watt amp it thumps fantastically.

My only complaint is the unit mounts with 2 screws only into the floor of the car. Mounted this way works but is a little loose on the top side. I added a straight connector bracket; screwed it into the enclosure and mounted that to the factory bolt that holds the trunk liner in.

Other than that, fantastic!

8 of 10 found this helpful

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Mustang GT

Peoria, AZ

Great sound and value

April 30, 2012

The JL stealthbox was way too expensive so i went with the MTX Thunderform for my 07 Mustang GT. I have a JL 12w3 in it with a JL Slash amp. The sound is great! You can adjust the sub to hit hard or less. You can make your seat vibrate and let cars around you hear or just have quality sound. The installers added another bracket on the top as it only had screws on the bottom and could fall over. Doesnt take up much room in the trunk. Highly recommend for anyone wanting a sub with a custom trunk fit.

6 of 8 found this helpful

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Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: MTX Audio Thunderform FMUST05BK12U (Black, Unloaded)