The best GrimmSpeed turbocharger kits for an older WRX or STI are the two kits on this shelf: the GrimmSpeed Overtake BB500 Turbocharger Kit and the GrimmSpeed Chase JB400 Turbocharger Kit, both titled for 2002-2007 WRX and 2004-2021 STI. This two-product collection is a focused shortlist, not a general turbo catalogue: two named kits for the same fitment span, for owners who have decided a turbo upgrade is next.
A turbocharger kit replaces the factory turbo with a more capable unit, and changes what the rest of the build must support: fueling, intercooling, exhaust flow and, above all, tuning. A kit is no standalone power guarantee, since the result depends on supporting parts and calibration. Plan supporting parts alongside the turbo, starting with Performance Intercoolers, and read enhancing boost control with a GrimmSpeed boost controller for the control side of a build like this.
Brands to know
GrimmSpeed is the only brand on this shelf, and the two kits show its approach: complete, named turbocharger kits for a defined Subaru fitment instead of a bare turbo sold alone. The Chase JB400 and Overtake BB500 are distinct kits for the same 2002-2007 WRX and 2004-2021 STI span, so the choice is about which suits your build goals and supporting parts. GrimmSpeed is carried widely in this store for Subaru engine, exhaust and bay hardware, and these kits sit at the serious end of that range.
Garrett is the wider turbocharger shelf to cross-shop in this store, carried for turbochargers across a broad range of builds. Garrett is the comparison point for pricing a turbo alone rather than as a kit. Comparing kit against standalone turbo clarifies what else you must source separately.
Blouch Turbos is another turbo specialist carried here, and its shelf is the natural next stop for Subaru owners comparing upgrade turbos. Blouch is known here through its turbo range, not general parts. Use it as a second specialist opinion, and confirm fitment by year and model on every listing.
COBB Tuning matters to a turbo build even though it sells no turbo on this shelf, because a turbo change needs calibration and monitoring. COBB is the tuning-ecosystem name in this store, known for the Accessport and its supporting hardware. Budget for the tuning side from the start, and see Turbosmart for the boost-control hardware that often changes at the same time.
FAQ
Which cars do these two kits fit?
Both kit titles state 2002-2007 WRX and 2004-2021 STI. That is a wide span with detail differences across years, so check your year and model against the individual listing before ordering.
Is a tune required with a turbocharger kit?
Yes. A different turbo changes airflow, so the car needs a calibration matched to the kit and its supporting parts before it is driven hard. Treat tuning as part of the kit cost, not an optional extra.
What supporting parts should I plan for?
Intercooling, fueling and exhaust flow usually partner a turbo change, along with boost control. The exact list depends on your current build, so map it out before the turbo goes on.
How hard is installation?
This is workshop-level work, not a driveway bolt-on: access, fasteners, oil and coolant lines and the tune all need care. Most owners have a kit like this fitted professionally.
GrimmSpeed
