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RTR Rear Diffuser (15-17 GT Premium, EcoBoost Premium)

Item 387381
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Market Price $329.99 You Save 15% ($50.00)
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$279.99 (each)

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      Review & Installation Video

      Hey guys, Justin with here, with my detailed review of the RTR Rear Valance Diffuser, fitting your premium package 2015 and up Mustang. So, who is this rear valance going to be for? Well, I would say it's going to be for anyone out there who really enjoys what Vaughn and his team at RTR have done with the S550, in regards to overall styling, and maybe wants to emulate that on his or her own ride. In addition, I'd say it's an excellent option if you're like me and you really didn't enjoy the factory color-matched rear valance, and want to replace it with something that's going to be a little bit more aggressive. Now when talking with Vaughn directly about his inspiration for the new RTR Mustang, he made it very clear to me that he wanted to do something pretty crazy with the rear of the car and give it more of an exotic look, in his own words. So by going with this fin-style rear diffuser valance, he definitely accomplished that and gave it more of a race car-inspired look in the rear. Now I think personally this thing looks a lot better when paired with the RTR rocker splitters, but again that is up to you, as it is going to add roughly 300 bucks to the final price tag. On the topic of price guys, this thing is definitely going to come in at the top of the food chain in regards to rear diffusers. Here on the site, it will be nearly double the price of the Roush rear valance, however you have to keep in mind that Roush rear valance can only be used with a quad-tip exhaust setup, so you have to factor that into the price. On the other hand, the RTR rear diffuser here can be used with your factory or aftermarket single-tip exhaust system, so you don't have to worry about anything there. Breaking down some of the finer details here, guys, you will find a durable, injection-molded ABS plastic for the build, and it has been finished off in the same textured grain black plastic as the rest of the exterior plastic on your S550, such as the chin spoiler, lower rockers, things like that. I do want to remind you, this will only work on premium package rear bumpers, as they are a little different from some of the base cars, so definitely don't forget about that. And also keep in mind, this thing will work with factory backup sensors, should not interfere with their operation whatsoever. When it comes time to get dirty, guys, here's what you need to know. Now, there is some permanent modification needed to get this thing installed. Basically you're going to be cutting off that color-match portion of the factory valance and replacing it with the RTR unit here. So an air saw, Dremel, something similar is going to be your best friend here. You're definitely going to need a 7-millimeter socket, along with a panel removal tool. Now, it probably sounds a lot more complicated than it really is, but nevertheless since there is some cutting involved, I'll call it two out of three wrenches on the difficulty meter, and maybe a couple of hours from start to finish to get this thing installed. So to wrap up, the RTR rear diffuser, or rear valance, guys, I really like what this thing does to the rear of the car. My one major pet peeve with the S550 from an appearance standpoint when it was released, was that color-matched factory valance. This thing totally replaces that, fixes that, in my opinion, and adds some aggressive styling to boot. So be sure to check out more from RTR for your S550 here at

      Product Information

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


      • RTR Signature Modern Aggressive Styling
      • Injection Molded TPO Material
      • Features a Grained Texture
      • OEM Fit and Finish
      • Straight Forward Installation
      • Backup Sensor Compatible
      • Fits 2015-2017 GT and EcoBoost Mustangs
      • Designed for Premium Chassis Packages Only (Trim Levels: 200A/201A/400A/401A)


      Ready To Rock! Install the same exact Rear Diffuser that is featured as original equipment on the Ford Mustang RTR to your very own late model muscle car. Designed and developed by Vaughn Gittin Jr., this Diffuser will add a modern, yet aggressive race inspired appearance to your ride.

      Quality Construction. RTR manufactures its Diffuser from OEM quality, high pressure injection molded, high-strength thermal plastic olefin (TPO) for its long lasting durability. This RTR Rear Diffuser features a grained texture for an OEM look and to hide rock and stone impacts that occur during daily driving.

      Straight Forward Installation. Installation of the RTR Rear Diffuser is simple and straight forward. However, it will require permanent modification to the stock rear bumper cover to remove the factory diffuser. Installation can be completed in about two hours.

      Backup Sensor Compatible. This RTR Rear Diffuser can be installed on Mustangs equipped with or without factory installed back-up sensors and will not affect sensor operation.

      Application. This RTR Rear Diffuser is specifically designed to fit 2015-2017 GT and EcoBoost Mustangs equipped with the factory Premium Chassis Packages only (Trim Levels: 200A/201A/400A/401A).

      Please Read. If you are having trouble determining what style bumper your Mustang is equipped with please refer to the comparison image above.


      Fitment: 2015 2016 2017

      RTR 387381

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (83)

      Write a Review

      Ratings Summary

      4.9 out of 5 overall rating from 83 customers

      Installation Time: Afternoon

      Installation Cost: $250-$500

      • May 14, 2020

        4 2016 GT - joe Installation Time: Afternoon

        Pricey, but aggressive.

        Love it. Fitment was perfect, finish was really high quality. Install was annoying, but it wasn’t that bad. The cutting is not as daunting as it may seem, very straight forward. The downside, however, is the price. It is quite high for what it is, but then again.. you get what you pay for.

        Helpful (0)
      • April 15, 2020

        4 2016 GT - Activeway Installation Time: Afternoon

        Great appearance

        Looks way better than the paint matched stock diffuser. Install was relatively easy, although a few bolts are tough to reach. I highly recommend buying a very small socket to get in there.

        Helpful (3)
      • January 03, 2020

        5 2015 GT - Hankey

        Rear Diffuser

        Easy install. Didn't take long at all. The worst part of it is permanently cut off a piece of your bumper. painful to watch. The only thing i would say was it pokes out of the car a little more than i expected. But overall very happy with the look and fit of this.

        Helpful (3)
      • December 19, 2019

        5 2017 GT - EmilyD Installation Time: Less than 1 Hour

        Way better than stock

        I hated the car color underneath the car, the black looks tougher and gives it more character. Took about hour and a half to install, not too bad.

        Helpful (3)
      • November 12, 2019

        5 2017 GT - Shadymouse Installation Time: Afternoon

        PITA Install but good looking

        Install was going well as far as unscrewing some of bolts and push clips. However, when I ran into unclipping the original diffuser, all frustration kicked in. You quickly realize why they suggest removing the bumper. The clips wouldn't be as hard to get off if you were standing up and had good leverage, but being underneath the car trying to slide and pry the clips off; quickly became a daunting task. Having a second pair of hands definitely helps if you intend on keeping the bumper on.

        Helpful (3)
      • September 12, 2019

        5 2016 GT - HpablaH Installation Time: Shop Install Installation Cost: $250-$500

        Rtr rear diffuser looks AGGRESSIVE

        Awesome look to make the rear end more aggressive. I highly recommend to buy this along with the Raxiom revser light/running light. It's the perfect combo.

        Helpful (4)
      • May 01, 2019

        5 2015 GT - DerekB

        Great Diffuser!

        Relatively easy install (highly recommend buying a Dremel for this), and definitely worth the effort. Looks great and makes the rear so much more aggressive.

        Helpful (3)
      • April 03, 2019

        5 2017 GT - Evan Installation Time: Afternoon

        RTR Diffuser

        Fit n finish looks factory. Love the new styling, and installed just as advertised.

        Helpful (3)
      • March 18, 2019

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

        Most aggressive feel!

        When I installed my RTR rear diffuser it was exactly what I needed to toughen up the look of my rear end. Just about all my mods are RTR so I am very loyal to an amazing brand. Install was fairly simple, little scary cutting into the rear bumper but doing so was a lot easier than it sounded. The only annoying part was trying to clip in the new rear diffuser with the stock one. The clips were stiff and required a bit of muscle to get them in, but they will eventually pop into place. 10/10 would recommend

        Helpful (4)
      • February 08, 2019

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

        RTR rear diffuser

        This diffuser looks great fit and finish perfect easy install

        Helpful (5)

      Questions & Answers (25 answers)

      5 Top Rated Questions

      Will this diffuser fit with a quad tip exhaust?

      • The RTR Rear Diffuser, is not designed for a quad tip exhaust and would require modification.

      Helpful (1)

      Will this fit on the 2015 gt performance package?

      hi! may i know the box dimensions weight of this product? its for shipping purposes. thanks

      • Packaged weight is 5 lbs. Dimensions are: 44" L x 14.25" W x 5.25" H.

      Helpful (0)

      hi! may i know the box dimensions the weight for shipping purposes? thanks

      • The packaging occasionally changes over time for various reasons, so your best bet if you ever need these dimensions would be to contact our customer service team to make sure you are getting the most up-to-date answer.

      Helpful (0)

      I was Q and received no answer. So is there any rear diffuser's that will be offered in the future for the base model bumper?

      • At this time, we are unaware of any models in the works for base model bumpers.

      Helpful (0)
      10 More Questions
      It says this will fit Trim Levels: 200A/201A/400A/401A. Where can I look to see if I have one of these? 1 answer
      Will this fit on the 50th anniversary edition GT? 1 answer
      Hello !! I don’t know very much about this , should I disconnect the battery to remove the bumper ? 1 answer
      Any idea on how I could get this to fit my v6 base model other than purchasing a premium bumper? 1 answer
      Will this fit a 2018 ecoboost (w/ PP)? 1 answer
      Will this RTR Rear Diffuser fit my 17 ecoboost with the performance package ?! Please let me know ! Thanks 1 answer
      Will this diffuser fit my 2015 V6 Mustang? (not premium) 1 answer
      In the video, I’m not sure whether it’s a cutting process, so dose the installation needs to destroy the original bumper? Thanks 1 answer
      When will we get the option for the non-premium mustangs? (RTR Rear Diffuser) 1 answer
      Would this work with a tow hitch (used to haul mountain bikes)? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Rear Diffuser

      Tech Specs

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