Free Shipping On Orders Over $49. Details

Talk to a Mustang Enthusiast
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Win $6,000 In Store Credit Enter Now

RTR Rear Diffuser (18-20 GT; 19-20 EcoBoost w/ Active Exhaust)

Item 403279
Call a Mustang Enthusiast at 1-877-887-1105
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Market Price $349.99 You Save 14% ($50.00)
Our Price

$299.99 (pair)

FREE Shipping

Will this fit your Vehicle?

Select a different vehicle Help?
Update or Change Vehicle
In Stock

Ship to: Ashburn - 20149
Sorry, please enter a valid US or CA postal code
We're sorry, zip can't be updated at this time.
    Create a list
    Add to New List

    Saved - View your saved items

    We're sorry. We couldn't save this product at this time.

      Product Information

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


      • RTR Aggressive Track Inspired Styling
      • Durable Injection Molded TPO Material
      • Features a Grained Texture
      • Straight Forward Installation - Cutting is Required
      • Sold as a Pair; Driver and Passenger Side Included
      • Fits 2018-2020 GT Mustang and EcoBoost Models with Dual Quad Exhaust


      Modern Aggressive RTR Styling. Add an aggressive track inspired appearance to your GT Mustang with the same exact Rear Diffuser that is featured as original equipment on the 2018-2020 Mustang RTR. Designed and developed in conjunction with Vaughn Gittin Jr., this RTR Diffuser was designed to offer a tastefully more pronounced Rear diffuser for those who want a bit more in comparison to the subtle factory rear diffuser.

      High Quality TPO Construction. RTR manufactures their Rear Diffuser from an injection molded thermal plastic olefin (TPO) material using the original OEM CAD data from Ford to ensure a perfect fit. TPO is an extremely strong material known for its light-weight, superior durability and impact resistance - making it perfect to withstand the hazards of daily driving. This Rear Diffuser is completed in a fine grained stippled texture for a factory look that helps to hide the appearance of rock and stone impacts.

      Straight Forward Installation. Installation of the RTR Rear Diffuser is simple and straight forward. The Diffuser installs easily with a combination of hardware and 3M automotive bonding tape. However, it will require permanent modification to the stock rear bumper cover to remove a section of the factory diffuser. Installation can be completed in about two hours.

      Application. This RTR Rear Diffuser is designed to fit 2018-2020 Ford GT Mustang and EcoBoost models equipped with dual quad exhaust tips only. Driver and passenger side Diffusers are included.


      Fitment: 2018 2019 2020

      RTR 403279

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (5)

      Write a Review

      Ratings Summary

      5.0 out of 5 overall rating from 5 customers

      Installation Time: Less than 1 Hour

      • May 01, 2020

        5 2018 GT - RP Installation Time: Afternoon

        RTR Rear Diffuser

        I didn't have an air reciprocating saw so I used a Dremel oscillating tool to cut the fins off of the oem diffuser. It was a simple surgical cut. I removed the 4-7mm head screws from the diffuser retaining the 2 long outer screws. Installed the brackets on the new diffuser's loosely, cleaned all surfaces, applied activator, removed 3M tape protector and installed new units reinstalling screws. Extremely tight fit. Final look really wowed me.

        Helpful (1)
      • April 14, 2020

        5 2018 GT - speedracergt Installation Time: Less than 1 Hour

        great product

        the was the easiest install just use a new razor knife instead of a saw it worked really nice..

        Helpful (3)
      • May 02, 2019

        5 2018 GT - JoshB Installation Time: Afternoon

        RTR Rear Diffuser

        Aside from cutting, install is a breeze. Just wish they would have told you about your reverse light wiring being right behind one of the fins. I ended cutting completely through that and having to solder them back together. Love the look!

        Helpful (4)
      • October 19, 2018

        5 2018 GT - BruceH Installation Time: Less than 1 Hour

        More aggressive rear

        Rear end looks a lot stronger with these installed. Install was very simple using a new sharp razor blade knife to cut out diffusers instead of using a electric cutting tool

        Helpful (16)
      • September 03, 2018

        5 2018 GT - GeevanT Installation Time: Less than 1 Hour

        Amazing product

        The diffuser just went in perfect and I did not have any problems putting it on, and it looks amazing.

        Helpful (16)

      Questions & Answers (4 answers)

      4 Top Rated Questions

      Will the Roush valence aero foil kit fit perfectly with this diffuser design?

      • Unfortunately, the Roush rear valance aero foil kit will not fit properly with this RTR rear diffuser product due to this part interfering with the install of the Roush kit.

      Helpful (1)

      Could this item work for my 2019 mustang GT with out active exhaust

      Is there actual cutting involved like the 15-17 rear diffuser from RTR? Based on the pics it looks like it slips over the stock ones and is held by double sided tape.

      • This RTR Rear Diffuser is only compatible with 2018-19 models.

      Helpful (0)

      why won't this fit a 2018 eco boost with a quad exhaust?

      • This diffuser is designed for the 18-19 Mustang GT models.

      Helpful (0)
      Post Your Question

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Driver / Left Side Rear Diffuser
      • (1) Passenger / Right Side Rear Diffuser
      • (2) Diffuser Brackets
      • (4) 5mm x 10mm Short Screws
      • (2) 5mm x 20mm Long Screws
      • (4) 5mm Washers
      • (1) Adhesion Promoter

          Related Mustang Categories