Ferrea Endurance Dual Spring Kit - 04-21 Subaru WRX STI EJ257 - KT4020 13" MB1-XTR4 kit features an Xtreme

MB1-XTR4 kit features an Xtreme pressure plate for the most demanding driver

SPAL 325 CFM 6

Skunk2 has been leading the industry with its fully adjustable Camber Kits

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Extreme thermal resistance and stability:

Ferrea Endurance Dual Spring Kit - 04-21 Subaru WRX STI EJ257 - KT4020 13" MB1-XTR4 kit features an XtremeFerrea Racing Valve Springs Kits bring together some of our best valvetrain components to help maximize performance specific to your engine application. Our knowledge and expertise have allowed us to build valve springs kits using components of premium quality and durability that exceed standard industry requirements. Ferrea Subaru WRX STI Endurance Dual Spring Kit Fitment: 2004: Subaru: Impreza: WRX STI, 2005: Subaru: Impreza: WRX STI, 2006: Subaru: