Steeda 'Stop the Hop' Street Starter Kit | Mustang
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Authorized Dealer • Expert Installation • Thousand Oaks, CA
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805-267-9762
FFP · AUTHORIZED DEALER The leader in Ford performance · Over 35 years · MAP pricing SHOP ALL STEEDA →
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Part #555-4455-S550

2015-2026 Ford Mustang – Steeda 'Stop the Hop' Street Starter Kit

Fits These Vehicles 2015-2026 Ford Mustang GT500/Bullitt/GT/EcoBoost/V6
Price $614.95

Available

Questions about this part?

Talk to a builder who installs these daily. Free advice, no pressure.

Free consultation Same-day quotes Expert install
  • 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
Moderate
Time
3 Hours
Warranty
Limited Lifetime

Overview

This is where the Stop the Hop Starter Kit comes in. Our team of engineers got together and came up with the best 3 parts for eliminating unwanted wheel hop in the new S550/S650 Mustang. 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 Mustang 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.

Which “Stop the Hop” Kit is for you?

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. Second is our tried and true IRS Subframe Bushing Support System. This 8 piece kit was a first of it’s kind in the performance aftermarket and so innovative and popular we patented it’s design! Made in house from billet 6061 aluminum and featuring stainless steel hardware, this kit fills all the factory voids in the IRS subframe mounting locations. It’s job is to prevent up and down movements of the subframe. The 3rd and final piece to this kit is the strongest support brace for the S550/S650 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. The best part about this kit, is the price. These 3 parts were the first of their kind for the S550 Mustang and nothing will prevent unwanted subframe movement or wheel hop better than this kit.

On the Car

Key Benefits

555-5754 – Steeda IRS Subframe Support Braces
555-4437 – Steeda IRS Subframe Bushing Support System
555-4438 – Steeda IRS Subframe Alignment Kit
Eliminate wheel hop while not increasing NVH
Eliminate subframe movement
Simple install
Squares subframe to the chassis
No permanent modifications

Specifications

Installation Difficulty
Moderate
Estimated Install Time
(approx.) 3 Hours
Tools Required
Basic Shop Tools

Video

Fitment

2015-2026 Ford Mustang GT500/Bullitt/GT/EcoBoost/V6.

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.

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Price$614.95
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OVER 35 YEARS IN FORD PERFORMANCE. RACING EVEN LONGER.
— Steeda Autosports · sold & installed by FFP
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