Serious Cooling for Serious STI Builds
The 2015–2021 WRX STI is one of the most capable Subarus ever built, but the stock cooling setup leaves plenty of room for improvement. That’s why we put together the GrimmSpeed Max Cooling Bundle — pairing our Top Mount Intercooler Kit with the CSF 31mm High-Performance Radiator, designed to keep your EJ25 running stronger, longer, and cooler under pressure.
This combo eliminates two major factory weak points, delivering reliable performance whether you’re canyon carving, daily driving, or chasing numbers at the track. It's designed to keep your STI cool and consistent, no matter how hard you drive. The GrimmSpeed TMIC drastically reduces intake temps, while CSF’s 31mm all-aluminum radiator boosts coolant efficiency with track-tested durability. It's a must-have pairing for drivers who demand more.
What’s Included
GrimmSpeed Top Mount Intercooler Kit – 2008–2021 STI
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Durable bar-and-plate core for optimal thermal efficiency
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Cast aluminum end tanks with integrated BPV flange
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Direct bolt-on install using factory locations
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Wrinkle black powder-coated finish
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Compatible with factory and most aftermarket charge pipes
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All hardware and gaskets included
CSF 31mm High-Performance Aluminum Radiator
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1-row, 31mm core featuring CSF’s B-Tube Technology
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Full TIG-welded construction with deep-drawn aluminum end tanks
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Wind tunnel, thermal cycle, and vibration cycle tested for real-world durability
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Brazed in a CAB furnace using military-grade clad aluminum (JIS 3003 minimum)
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CNC-machined fittings and racing-style drain plug
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Burst and impulse cycle tested 10,000+ times
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Salt spray tested for corrosion protection
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30-point dimensional inspection for OEM fitment—no trimming or mods required
Fitment
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2008–2021 Subaru STI (EJ25 Engine)
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Both components install with factory hardware and mounting points
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100% direct bolt-on — no tuning or fab work required