Steeda Handling Ultimate Kit | Mustang
YOUR BUILD STARTS HERE Expert Installs Thousand Oaks, CA
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Authorized Dealer • Expert Installation • Thousand Oaks, CA
Discount Code: FFPERFORMANCE
805-267-9762
FFP · AUTHORIZED DEALER The leader in Ford performance · Over 35 years · MAP pricing SHOP ALL STEEDA →
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Part #555-2129-G

2015-2023 Ford Mustang GT350/Mach 1 – Steeda Handling Ultimate Kit

Fits These Vehicles 2015-2023 Ford Mustang GT350/Mach 1
Price $1,194.95
  • Engineered and manufactured in Valdosta, Georgia
  • CNC-machined billet construction where applicable
  • Tested on Steeda's SCCA Majors race program
  • Steeda authorized dealer — exact MAP pricing

Limited Lifetime Warranty

Backed by Steeda — FFP is an authorized Steeda dealer and warranty claims are honored direct.

— Function Factory Performance

Authorized Steeda Autosports dealer. MAP pricing — the same price as steeda.com. Expert install available at our Thousand Oaks, CA shop. Questions on fitment or setup? Chat with Senna or call our specialists.

Overview

The full breakdown.

Install
Tech Recommended
Time
6 Hours
Warranty
Limited Lifetime

Overview

This is where the Handling Ultimate Kit comes in. Our team of engineers got together and came up with the best parts for eliminating unwanted wheel hop and bushing deflection in the new S550 Mustang to help you take corners faster and get tack sharp handling. A kit that gives you the fundamental foundation for ultimate traction and suspension compliance. As we have explained before, the factory IRS subframe, (often inaccurately referred to as a cradle), mounts to the S550 chassis with 4 mounting locations utilizing 4 soft rubber bushings with plenty of voids, even in the bolt holes. The kit we put together addresses these issues and more.

First is our Alignment dowel kit. This fills the factory bolt hole voids with CNC machined delrin inserts that will square up the rear subframe to the chassis. By filling these voids we are also limiting the side to side and front to back movement of the subframe that is present under hard acceleration and braking. The 2nd component of this kit is the strongest support brace for the S550 IRS on the market!! Made in-house from chrome-moly steel, this brace is designed to support the factory subframe by directly tying it into the chassis at key mounting locations. Using factory mounting locations on the factory frame, this 5 point brace supports the front factory mount and the lower control arm mount as well. A simple bolt-in design, this brace ties the subframe to the chassis in the best possible way.

Steeda’s Rear Toe Links are the 3rd item in the kit. They help you improve your launch and allows you to control the toe of your Mustang during launches. Improve your 60-foot times and get down track faster with this upgrade from Steeda.

Key Benefits

555-5754 – Steeda IRS Subframe Support Braces
555-4449 – Steeda GT350/Mach 1 Subframe Bushing Support System
555-4438 – Steeda IRS Subframe Alignment Kit
555-4129 – Steeda Billet Aluminum Vertical Links with Urethane Bushings
555-4120 – Steeda Adjustable Rear Toe Links
Eliminate wheel hop with little to no increase in NVH
Eliminate subframe movement
Simple install
Squares subframe to the chassis
No permanent modifications
More predictable handling
Greater control and stability

Specifications

Installation Difficulty
Tech Recommended
Estimated Install Time
(approx.) 6 Hours
Tools Required
Basic Shop Tools

Video

Fitment

2015-2023 Ford Mustang GT350/Mach 1.

Note: Steeda IRS Subframe support braces will not fit convertible

Why Steeda
The leader in Ford performance.

Steeda has been engineering and manufacturing Ford performance parts in-house in Valdosta, Georgia for over 35 years — proven on their own SCCA Majors race team and trusted by enthusiasts who live and breathe Ford. CNC-machined billet construction, proprietary CAD-driven suspension geometry, and a relentless focus on the platforms they specialize in.

QS-9000 & ISO 9001 manufacturing · Limited lifetime warranty on Steeda-manufactured parts · Made in the USA

First-hand note

FFP fits Steeda parts every week in Thousand Oaks.

— Why we stock Steeda

OE-style engineering, in-house manufacturing, race-proven on Steeda's own SCCA program.

Steeda has been engineering Mustang — and now Explorer, Focus, F-150, and Maverick — parts in Valdosta, Georgia since 1988. CNC-machined billet, proprietary CAD-driven suspension geometry, and a factory SCCA Majors road-racing team that runs their own parts on the track every weekend. When you bolt a Steeda part onto your car, it's the same part Steeda's own race cars run.

We carry Steeda because the fitment is right the first time, the warranty is real (lifetime on Steeda-manufactured parts), and the install instructions don't leave you guessing. Drop the car at our Thousand Oaks shop and our techs handle the fit-up — or order with confidence and run it yourself.

Authority: Charles Siritho · McLaren Artura Trophy owner · Spotter for Branden Sorensen FD Pro (E46 LS+Whipple, 6th at Long Beach R1 2026) · 10+ yrs Mustang & Corvette specialist

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— FFP is an Authorized Steeda Dealer

Shop the full Steeda catalog at FFP.

The leader in Ford performance — suspension, intakes, exhaust, brakes, wheels, and more — for Mustang, Bronco, Bronco Sport, Explorer, F-150, and Maverick. Enthusiast-driven, race-tested. MAP pricing always. Expert installation in Thousand Oaks, CA.

BROWSE ALL STEEDA →
Price$1,194.95
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OVER 35 YEARS IN FORD PERFORMANCE. RACING EVEN LONGER.
— Steeda Autosports · sold & installed by FFP
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