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SpeedForm Sport Quarter Window Louver; Matte Black (15-20 Fastback)

Item 403355
Market Price $49.99 You Save 20% ($10.00)
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$39.99 (pair)

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      Review & Installation Video

      Hey, guys. Adam here with And today, we're taking a closer look at and installing the SpeedForm Sport Quarter Window Louvers in Matte Black finish for the 2015 and newer Mustang Fastback. You should be checking this out if you're the owner of an S550 Fastback and if you're looking to get more of a retro-styling in an appearance part for the side profile of your Mustang. Now, I will say while we have seen quarter window louvers on Mustangs for absolutely decades going back to the mid-60s, right? The classic Fastbacks. This, I think, has a little bit more of a modern spin on it. Now the sports styling from SpeedForm features this angular shape to the five spokes or the five slots in your louvers.I actually think this is a little bit more inspired by the angular new tail lights on the 2018 and newer Mustang, as well as the running lights and your headlights on the S550. I think that's a really cool detail built into the shape and styling for these louvers but that's just me, it's all personal preference. If you're not particularly the biggest fan of the angular styling here, SpeedForm does have a number of different designs for quarter window louvers, so there's a bunch of options to fit personal preference. Now this one does come in a nice smooth non-textured matte black finish but I will say it is paintable. So if you pick this up in the matte black, take it to your local paint shop and in this case, have it match to your race red or whatever exterior color of your choosing to match your S550. It's an ABS-construction vacuum form, so it's impact-resistant, it's UV-resistance so it won't fade over time. It obviously just looks really good on the side profile. Now price tag comes in right around 40 bucks for the pair. Super affordable mod. A lot of times you pick up exterior styling parts that can be upwards of a hundred, couple hundred bucks, not the case here, very affordable. Install, of course, gets one out of three wrenches on our difficulty meter. Goes on with 3M automotive bonding tape but I will say it can be very, very secure when you make sure that everything is cleaned properly. That's really the key. You want to make sure you're properly cleaning your quarter window and the backside of your louvers before applying the 3M. You want to make sure it gets to the best bond possible and any dirt and dust left behind between the 3M is gonna make sure that it's going to fall off and you don't want that happening, especially at highway speed. So make sure you're cleaning properly. Other than that, you don't really need any tools. I'd recommend an alcohol wipe or two, as well as maybe soap and water mixture and a squirt bottle to make sure everything is cleaned along with a clean microfiber. I'm gonna show you guys every step of the way so what do you say we get to it. Now the tools used in this install include a knife, the 3M tape included in the kit, an alcohol wipe or a soap and water mixture as well as a clean microfiber. All right, guys, the first step here, of course, is to grab your louvers. You're gonna flip them upside down and grab the 3M tape roll included in the kit. So you are gonna have to cut to length the small strips of 3M that are gonna go on the back and line the edges here. So what you're gonna do first is actually take an alcohol wipe, I recommend or soap and water mixture and you just want to make sure you're cleaning off the edges around your louver so that it can free it of all dirt and dust. You want your 3M tape to have a good bond. So I'm gonna take my alcohol wipe and go around the edges, but again guys, the soap and water mixture could also work. Just give it one good wipe around, take some of that off. Now what you're gonna do is peel back the 3M and measure it to length. That looks about right. You want to have a knife on hand and you're just gonna cut it. From here, take your strip and lay it in place. You want to make sure the 3M does not go over the edge, you don't want to see it when it's installed on the vehicle. All right, this last little strip here is a little bit curved, so you want to keep that in mind, you want to curve with it. All right, now you can repeat this for the other side and we're gonna peel off the red backing and stick it on our window. But first, we are gonna have to wipe down our window just like we wiped down the back of the louver. All right, so I'm gonna grab another alcohol wipe. We're basically gonna wipe down the edges of this quarter window getting all that dirt off so it can get a good bond. All right, guys, now what I like to do is peel off half of the red backing on the 3M and just fold it over so it's hanging outside of the edges here and I'll show you guys why in just a second. Do that for all of the strips. You don't want to peel it off too much, I'd say just about halfway is totally fine. Now you're gonna grab your louver and set it into place on your window very gently. You don't want to put too much pressure on it just yet. Get it in the position that you like, just give it a tap so it sticks in place. Now what we're gonna do is with that red ribbon sticking out, we're gonna peel that back and stick. Same thing here. Peel, keeping it in the same spot and stick. Peel, stick. Nice one. All right, put pressure all around the louver to stick it on the window and repeat for the other side. Well, guys, that's gonna wrap up my review and install for the SpeedForm Sport Quarter Window Louvers in a Matte Black Finish for the 2018 and newer Fastback. If you want to pick this one up for your own S550, you can do so right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Chevron Shaped Louvered Design
      • Matte Black Finish
      • Vacuum Form ABS Construction
      • Simple Peel and Stick Installation
      • Driver and Passenger Side Louvers Included
      • Fits all 2015-2020 Fastback Mustang Models


      Sporty Styling. Add a sporty appearance to your 2015-2020 Fastback Mustang with a set of SpeedForm Sport Quarter Window Louvers. Featuring a louvered chevron design, these C-Pillar Window Louvers will enhance the bold styling of your S550 Pony's body lines.

      Quality Construction and Materials. SpeedForm's Sport Quarter Window Louvers are manufactured from vacuum-formed acrylonitrile butadiene styrene (ABS) plastic for its light weight and long lasting durability. These Quarter Window Louvers are then completed in a smooth matte black finish for aggressive good looks.

      Peel and Stick Installation. No messy glue or drilling is required for installation. These SpeedForm Sport Quarter Window Louvers are designed to attach to the factory C-Pillar glass with the supplied 3M doubled sided automotive bonding tape for a quick and easy installation. Just clean the surface, peel the backing and stick in place - it's that easy.

      Recommended Styling Upgrade. When installing exterior quarter window louvers or scoops on your Mustang, it is recommended to add a set of quarter window blackout decals to hide the ugly back side that wasn't meant to be seen by human eyes. See part number 386505.

      Application. These matte black SpeedForm Sport Quarter Window Louvers are designed to fit all 2015-2020 Fastback Mustangs, including the V6, EcoBoost, GT, GT350 and GT500 models. Sold as a set of two, one driver side and one passenger side.


      Fitment: 2015 2016 2017 2018 2019 2020 Details

      MPN# 403355

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (58)

      Write a Review

      Ratings Summary

      4.5 out of 5 overall rating from 58 customers

      Installation Time: Less than 1 Hour

      • February 18, 2020

        1 2018 GT - DonnaC

        Does not fit like they say poor quality

        They do not fit like they say and the tape is poor quality too they do not fit a 2018 5.0 Gt mustang. I try to get my money back but they would not give it to me

        Helpful (0)
      • January 27, 2020

        5 2017 EcoBoost - rj Installation Time: Less than 1 Hour

        Love it

        Little bit long to arrive here my place but it’s worth it when the item comes.. It’s was easy install and the car make more cooler .

        Helpful (0)
      • January 13, 2020

        4 2015 GT - Caleb Installation Time: Less than 1 Hour

        Looks Good, but Supplied Tape is Inadequate

        I like how the plastic blends with the black trim, preventing it from looking cheap. It's a bit flimsy in quality, but once it's installed, it doesn't matter. The biggest concern with these was the supplied tape. It's not very wide, and when I installed these louvers, they didn't seem to be sticking very well. I went and bought wider 3m tape from NAPA and now they're sticking perfectly.

        Helpful (0)
      • December 28, 2019

        4 2016 V6 - JeromeVert Installation Time: Less than 1 Hour

        You get what you paid for

        Mine have been on for a month. Only problem is the tape isn't sticking that great on some areas. They don't flop around when you drive. They are made of bendable plastic but that doesn't really matter. They look nice and they are cheap.

        Helpful (0)
      • December 06, 2019

        3 2015 GT - StephenC Installation Time: Less than 1 Hour

        Looks great

        The quality is not the best. And even with extra tape the louvers curl in the front corners. Will probably remove and scrap eventually.

        Helpful (1)
      • November 14, 2019

        5 2016 V6 - Olivia Installation Time: Less than 1 Hour

        Better than expected!

        I really liked how they looked on my car, the material is light but very sturdy. Definitely would recommend.

        Helpful (0)
      • November 12, 2019

        5 2019 GT - Duy Installation Time: Less than 1 Hour

        Nice and clean

        Easy to install and looks awesome. Highly recommend for everyone

        Helpful (0)
      • November 11, 2019

        4 2019 GT - ScottF Installation Time: Less than 1 Hour

        Quarter window

        Easy to apply took less than an hour and looks great

        Helpful (0)
      • November 09, 2019

        5 2019 GT - Leift Installation Time: Less than 1 Hour

        Bang for your buck

        Easy install look good I added a little extra backing tape to be safe

        Helpful (0)
      • October 20, 2019

        5 2015 GT - Bamcam Installation Time: Less than 1 Hour


        Easy to install, looks really good. Can’t wait to make more improvements

        Helpful (0)

      Questions & Answers (3 answers)

      3 Top Rated Questions

      I've always been a little concerned that most of the louvers completely block any view. These appear to be shaped such that the driver may be able to see through them ie: they don't create a big blind spot? Is that the case?

      • The angle that the slots are positionedallows for a clear view through them. They do not cause much obstruction. 

      Helpful (3)

      Will this fit a 2019 bullitt?

      Will these hold up during a long road trip at highway speeds?

      Post Your Question

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Passenger Side - Quarter Window Louver
      • (1) Driver Side - Quarter Window Louver
      • (1) Roll of Automotive Bonding Tape

      Will It Fit My Mustang

      • Bullitt - 19, 20
      • EcoBoost - 15, 16, 17, 18, 19, 20
      • GT - 15, 16, 17, 18, 19, 20
      • GT350 - 15, 16, 17, 18, 19, 20
      • GT350R - 15, 16, 17, 18, 19, 20
      • GT500 - 20
      • V6 - 15, 16, 17

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