Full Disclosure: I bought the MMD carbon fiber ducktail spoiler from American Muscle without a discount. No press perks here.

I have officially been daily driving my 2014 3.7-liter Mustang for a year now. It still doesn’t have a name, and if I am being honest – I still don’t love it as much as “Marilyn.” When I purchased the 2014 Mustang, it came with a flat trunk, sans wing or spoiler. Since I got the car, I have wanted to add a wing or spoiler, but hadn’t seen one I really loved or was obsessed with.

Marilyn, my 2005 4.0-liter Mustang, had a three-piece carbon fiber Roush wing. Sure, it was a V6 with a dismal 200 horsepower or so, but the wing made a huge night and day difference that I felt at high speeds. I loved the performance and style and had thought a lot about doing the same for this new car, but I didn’t want to do the exact same modifications to this car.

I wanted something that would be functional, yet give the car a classic but aggressive look. I went with the Modern Muscle Design, MMD, carbon fiber ducktail spoiler available through American Muscle.

According to American Muscle, the spoiler is made entirely of carbon fiber that is vacuum infused with resin for strength and a quality finish.

Things To Consider:

American Muscle says the spoiler is compatible with all variations of the 2010-2014 Mustang and the MMD site boasts the spoiler has been built to “contour perfectly to your car’s factory body lines.” I found the fitment to be off which makes it challenging to install if you do not have pre-existing factory holes.

If you are lucky enough to have existing holes left in the trunk lid from a stock spoiler, American Muscle says California Special GT or GT Premium owners will find the holes left from the factory spoiler will not line up correctly for installation with this MMD Ducktail Spoiler.

Function or Form: 

Spoilers work as barricades to undesirable airflows and reshape airflow streams around the vehicle. This can help keep the rear of the car down and decrease drag by changing the effective vehicle shape.

To really determine the effectiveness of this spoiler you would need a variety of tests including wind tunnel testing to quantify performance. This will not affect straight-line low-speed acceleration, but you will feel improved stability and cornering at high speeds.

What You Need To Know: 

For this install, I enlisted the help of a friend who assured me he had performed this modification before and provided photos of a trunk mounted wing he had installed on a Scion FRS. Neither of us performs cosmetic modifications often, let alone drill holes in our cars frequently enough to know the best way to go about it.

After careful consideration, the method of installation shared is what we decided was the best.

What’s in the Box:

• 1 MMD Ducktail Spoiler
• 4 6mm-1.0 x 16mm Pan Head Bolts 
• 4 6mm Washers 
• 4 Self-adhesive foam pads
• 1 roll of 3M Double-sided foam adhesive
• 2 Alcohol Cleaning Wipes 
• 1 3M Adhesive Promoter Wipe 

Installation Time:

• 2-4 Hours

Difficulty Level:

• Light to Moderate mechanical skill required 

Tools Required:

• 10mm Socket wrench
• Phillips and Flat head screwdrivers
• Drill
• Painters Tape
• Blue Putty

Step One: Removal of Trunk Liner

Remove the plastic clips of the trunk liner using a clip removal tool or a screwdriver.

The center pin pulls up (but not removed) which allows the clip to be removed in entirety. Remove the liner, being careful of the emergency trunk release lever and the trunk latch mechanism.

Step Two: Drill Holes

Use painters tape, or similar, and apply to the trunk where the spoiler will be.

Place screws in the spoiler and add blue putty to the tops.

Place spoiler from the top, down on the trunk in the desired location. Be careful not to move the spoiler much as the blue putty will leave marks.

Press the spoiler lightly on the truck to ensure the putty is on the tape.

Remove screws from MMD spoiler and place back on the trunk to trace edges of spoiler.

Measure where the spoiler holes are relative to the edge of the spoiler.

Check the spoiler hole measurement against the blue putty mark on the trunk with the traced edge line.

Our putty marks were off but it gave us an idea of where to place the pilot hole.

Drill pilot hole with a small drill bit.

Use the appropriately sized drill bit to drill the mounting holes.

Remove tape and clean the surface area. Our mistake was drilling the pilot holes all at once followed by the more massive holes. I recommend drilling the first hole, bolt the spoiler in and then add the pilot holes based off that so you don’t end up with doubles as I did.

We measured everything five times, drilled once, and still missed the mark. We aren’t sure if that due to a flaw in our initial process or if it is a result of poor fitment. The spoiler fitment doesn’t align with the body just enough to mess with measurements and make the placement questionable. Not everything is created equally, so it is always good to check and measure throughout the process.

What I love about this spoiler style is that it lays flat against the trunk and hides any mistakes –  like enlarged or extra holes.

Step Three: Install the new spoiler

Apply the 4 foam pads to the bottom surface of the spoiler around the threaded insert holes and wipe the border of the bottom surface of the spoiler with the 3M adhesive promoter and allow to dry for 60 seconds.

Attach the 3M double-sided tape around the entire border of the bottom surface of the spoiler.

Before completion of the next step, it is recommended to try a dry fitting for alignment and sizing of the bolts. When all pieces appear to have a proper fit, proceed with the next step for final installation.

Remove the adhesive backing and align spoiler with the holes in the trunk. Using 6.0mm-1.0 bolts to secure the spoiler to the trunk. Do not allow adhesion of the double-sided tape until the spoiler is aligned in proper position. It is not easily repositioned.

After tightening all 4 bolts, close the trunk and apply pressure down on the spoiler to ensure complete adhesion of the tape.

Take care when placing the bolts in the spoiler. I recommend ensuring your hands are clean as a bolt slipped and was lost within the trunk. We tried to retrieve it with a magnet and lost the magnet inside the trunk as well. I have had the spoiler on the car for several weeks now and each time I open or close the trunk, I can hear the bolt rolling around and rattling.

Final Step: Reinstall Trunk Liner 

Reinstall the plastic plugs over the spoiler bolts and reposition the trunk liner. Be mindful of the emergency trunk release lever and the latch mechanism. Then Replace all 13 clips to secure the liner. ​