Steeda Mustang IRS Base Pack
The IRS base pack combines alignment sleeves 555-4438 and bushing supports 555-4437. It centres and supports all four subframe mounting positions to limit sideways movement and rotation, helping reduce wheel hop without additional noise or vibration according to Steeda.
CNC-machined Delrin sleeves fill the original bolt-hole clearance. Factory misalignment can reach approximately half an inch, so check wheel alignment after initial installation. The sleeves subsequently return the subframe to the same position after removal. Delrin is lightweight and avoids a dissimilar-metal corrosion interface. No permanent modifications are required, with an installation estimate below two hours. Steeda states European ECE approval.
Package difference
The full pack adds 555-5754 chassis braces. These fit coupes only, so convertibles require the base pack.
The braces connect the sill structure, front subframe mount and rear control-arm/toe-link mounting area. The original bracket remains supported and complete subframe removal is unnecessary.
Instructions and videos
- Instructions (PDF) 1
- Instructions (PDF) 2
- Instructions (PDF) 3
- Product video on YouTube 1
- Product video on YouTube 2
- Product video on YouTube 3
- Product video on YouTube 4
- Product video on YouTube 5
- Product video on YouTube 6
Related vehicles
- S550 GT, EcoBoost, Bullitt and GT500 2015–2023, plus S650 GT, EcoBoost and Dark Horse from 2024
GT350 and Mach 1 require the different 555-4449 bushing-support kit.
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