Steeda S550 Mustang Race Differential Bushing Insert System - Aluminum GT/EcoBoost (2015-2021)

4 Review(s)
$25.00 (19%)
Steeda Autosports has once again taken the S550 Mustang to the next level of performance with our exclusive Billet Aluminum Differential Mount Bushing Insert System for all 2015+ Mustangs GT/EcoBoost!

Part Number: 555 4440
Write a Review


Steeda Autosports has once again taken the S550 Mustang to the next level of performance with our exclusive Billet Aluminum Differential Mount Bushing Insert System for all 2015+ Mustangs GT/EcoBoost! When our engineers sat down to design our street kit, we knew we needed one for the hardcore racers out there, too!

Steeda's race kit installs in under 1 hour, is adjustable and can be easily removed - it simply doesn't get any better than this!

It eliminates pinion angle changes, wheel hop, differential deflection all while increasing traction! Made in-house from billet 6061 aluminum.

Steeda's kit adds the strength and support the OEM bushings need to perform the way our hardcore racers intended. Once again, this is not a permanent modification - there is no drilling, cutting or pressing required. Simply loosen and remove a couple bolts and this kit installs in less than 1 hour. Aluminum bushings are included for both the front and rear differential mounting locations. Grade 10.9 hardware is included with zinc-plated washers.

Note: This is a race-only part. It will increase NVH and gear noise. For street and competition use, try our 555 444 3 kit with urethane bushings.

Note: Does not fit GT350 or Mach 1. Due to changes in the OE subframe bushings, the bushing inserts will not fit 2021 GT500's or 2022 Mustang's.

Product Benefits
  • Limits IRS differential movement while increasing traction and eliminating wheel hop
  • Designed for the abuse seen racing down the 1/4 mile
  • Easily removable, not a permanent modification
  • 100% designed, manufactured and made in the USA
  • Installs in 1 hour or less

CA Residents: Cancer and Reproductive Harm WARNING

Fitment & Features


Manufacturer: Steeda Autosports
Made in USA: Yes

Installation Information:

Level of Difficulty: Easy
Install Time: About 2 Hours
Tools Required: Basic Shop Tools
Print Instructions: Installation Instructions

Vehicle Fitment:

Fits Model Year: 2015, 2016, 2017, 2018, 2019, 2020, 2021

Customer Reviews

Rating Snapshot

Select a row below to filter reviews.

Average Customer Ratings


I am please to say the thud is gone
So I was unaware that people had seen an improvement in the thud after installing the diff bushing so I hadn't really paid attention to it at all. My car is a GT PP with a ver obvious and annoying thud. Well, after paying more attention to it today I am pleased to say the thud is gone. That being said, I did notice a more pronounced shift if that is possible. Maybe a little more notchy, but I like it. Feels like the shifter drops into place easier. Bushings look to be a great investment and mod!
Did you find this helpful?  3 of 3 Found Helpful
time to give props to Steeda
My car would not hook up at all. Basically if you gunned it in 1-3 you were burning rubber. The two kits I ordered were Stop the Hop and Differential Bushing Insert System. I opted for the metal bushing. I was worried about too much noise but it seems fine to me. Basically if you have loud exhaust I do know if you can even tell the difference. If anything the car sounds more connected to the transmission if that makes sense. It hooks up at least 70% better now and that's conservative. For those that are wondering about alignment, I had the car aligned at it's zeroed out perfect. Anyway it will still burn tires but it is night and day trying to manage. With this I do not have the feeling the car is going to do a 180 at any given time.
Did you find this helpful?  2 of 2 Found Helpful
Most noticeable improvement in the car
IRS differential bushings, aluminum: Most noticeable improvement in the car. Probably the best suspension mod I have made. Yes, you shift hard you'll feel a slight clunk as power hits to the rear end and has nowhere to go but to the tires, but that's exactly what I want. Car barely squats at this point and yet is still very comfortable for easy cruising. I have noticed a bit of driveline whine since installing them, but it's so light I don't even notice. Besides, I have a Corsa to listen to and that definitely drowns it out.
Did you find this helpful?  3 of 3 Found Helpful
WOW. Huge difference on launch!
Just installed the Steeda full aluminum IRS bushings and took Anna for a rip before installing Steeda's IRS subframe braces. WOW. Huge difference on launch! I can honestly say I'm a lot more impressed than I expected to be. Just pulling out onto the street I could feel it was a bit more firm, but when I pulled and hit second, that's when I could really feel them working. There was almost no squat and she just wanted to go. The ass did kick out a bit, but my new wheel/tire combination will fix that. Ride quality really hasn't suffered from this kit either. I expected harshness since it's full aluminum, but it's really not that bad. Yes, you can tell they're there, but not enough to bother me a long drive or anything. Kudos Steeda! Bringing her aback in the shop to install the IRS braces.
Did you find this helpful?  2 of 2 Found Helpful
There are no reviews for this product!

Related Items

123123 - 1
Back to TOP
0 Items