Factory Rubber Out, GrimmSpeed Silicone In — The STI/Forester XT Cooling System Upgrade
The GrimmSpeed Radiator Hose Kit in Black for 2008+ Subaru WRX STI / 2009-2013 Forester XT replaces every factory rubber radiator hose with reinforced silicone hoses that resist heat cycling, maintain flexibility over time, and won’t degrade under the demands of a turbocharged engine. Complete kit with color-matched clamps — all hoses for the full radiator circuit in one box.
Silicone vs Rubber — Why the Material Upgrade Matters
The factory radiator hoses on Subaru turbocharged engines are rubber — functional at stock coolant temperatures and pressures but prone to hardening, cracking, and degradation over time, particularly on cars that see elevated coolant temperatures under sustained boost. GrimmSpeed’s silicone hose kits use reinforced silicone that maintains flexibility across a wider temperature range, resists the heat cycling that degrades rubber over time, and holds its shape under elevated coolant pressure without ballooning. The color-matched hose clamps included in the kit finish the installation cleanly.
Direct Replacement — Full Kit in One Box
Each GrimmSpeed radiator hose kit includes every hose needed for the complete radiator cooling circuit on the specific platform — not a partial kit that requires sourcing additional pieces. The hoses are sized and shaped for direct fitment at the factory connection points, so installation is straightforward without modification to the cooling system. Color-matched hose clamps are included.
Key Features
- Platform: 2008+ Subaru WRX STI / 2009-2013 Forester XT
- THIS LISTING: Black — other colors/finishes available
- Reinforced silicone construction — resists heat cycling and degradation
- Replaces all factory rubber radiator hoses in the cooling circuit
- Color-matched hose clamps included
- Direct fitment at factory connection points — no modification required
Fitment Notes
- Platform: 2008+ Subaru WRX STI / 2009-2013 Forester XT
- Direct replacement at factory hose connection points
- Complete kit — all hoses for the radiator circuit included
- Confirm specific model year fitment from product title before ordering
Straight From Subispeed
The GrimmSpeed radiator hose kit is the correct upgrade for any STI/Forester XT build addressing the cooling system. Factory rubber hoses have a finite service life on turbocharged engines and silicone is the correct long-term replacement. Black color, color-matched clamps, complete kit — open the box and install.
What’s Included
- GrimmSpeed Radiator Hose Kit — Black (complete set)
- Color-matched hose clamps
About GrimmSpeed
GrimmSpeed is a Pacific Northwest-based performance parts manufacturer that has been building Subaru-specific hardware since 2003. Founded by engineers who were actively building and racing Subarus themselves, GrimmSpeed’s catalog reflects the priorities of people who use the products they make — turbo inlets, downpipes, uppipes, boost controllers, intercoolers, and engine bay accessories designed specifically for the EJ and FA-series Subaru platforms. Every GrimmSpeed product is engineered, tested, and refined in-house, and their focus on Subaru means the fitment and function reflect a deep understanding of the specific platforms they cover. Subispeed carries the full GrimmSpeed catalog because their approach to product development consistently produces parts that perform as advertised and fit correctly out of the box.
| Year | Make | Model | Notes |
|---|---|---|---|
| 2008-2021 | Subaru | WRX STI | EJ257 |
| 2009-2013 | Subaru | Forester XT | EJ255 |
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